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2016-12-07can: raw: raw_setsockopt: limit number of can_filter that can be setMarc Kleine-Budde
This patch adds a check to limit the number of can_filters that can be set via setsockopt on CAN_RAW sockets. Otherwise allocations > MAX_ORDER are not prevented resulting in a warning. Reference: https://lkml.org/lkml/2016/12/2/230 Reported-by: Andrey Konovalov <andreyknvl@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Cc: linux-stable <stable@vger.kernel.org> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2016-12-06tcp: warn on bogus MSS and try to amend itMarcelo Ricardo Leitner
There have been some reports lately about TCP connection stalls caused by NIC drivers that aren't setting gso_size on aggregated packets on rx path. This causes TCP to assume that the MSS is actually the size of the aggregated packet, which is invalid. Although the proper fix is to be done at each driver, it's often hard and cumbersome for one to debug, come to such root cause and report/fix it. This patch amends this situation in two ways. First, it adds a warning on when this situation occurs, so it gives a hint to those trying to debug this. It also limit the maximum probed MSS to the adverised MSS, as it should never be any higher than that. The result is that the connection may not have the best performance ever but it shouldn't stall, and the admin will have a hint on what to look for. Tested with virtio by forcing gso_size to 0. v2: updated msg per David's suggestion v3: use skb_iif to find the interface and also log its name, per Eric Dumazet's suggestion. As the skb may be backlogged and the interface gone by then, we need to check if the number still has a meaning. v4: use helper tcp_gro_dev_warn() and avoid pr_warn_once inside __once, per David's suggestion Cc: Jonathan Maxwell <jmaxwell37@gmail.com> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05netlink: Do not schedule work from sk_destructHerbert Xu
It is wrong to schedule a work from sk_destruct using the socket as the memory reserve because the socket will be freed immediately after the return from sk_destruct. Instead we should do the deferral prior to sk_free. This patch does just that. Fixes: 707693c8a498 ("netlink: Call cb->done from a worker thread") Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05net: caif: remove ineffective checkPan Bian
The check of the return value of sock_register() is ineffective. "if(!err)" seems to be a typo. It is better to propagate the error code to the callers of caif_sktinit_module(). This patch removes the check statment and directly returns the result of sock_register(). Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188751 Signed-off-by: Pan Bian <bianpan2016@163.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05net: ping: check minimum size on ICMP header lengthKees Cook
Prior to commit c0371da6047a ("put iov_iter into msghdr") in v3.19, there was no check that the iovec contained enough bytes for an ICMP header, and the read loop would walk across neighboring stack contents. Since the iov_iter conversion, bad arguments are noticed, but the returned error is EFAULT. Returning EINVAL is a clearer error and also solves the problem prior to v3.19. This was found using trinity with KASAN on v3.18: BUG: KASAN: stack-out-of-bounds in memcpy_fromiovec+0x60/0x114 at addr ffffffc071077da0 Read of size 8 by task trinity-c2/9623 page:ffffffbe034b9a08 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x0() page dumped because: kasan: bad access detected CPU: 0 PID: 9623 Comm: trinity-c2 Tainted: G BU 3.18.0-dirty #15 Hardware name: Google Tegra210 Smaug Rev 1,3+ (DT) Call trace: [<ffffffc000209c98>] dump_backtrace+0x0/0x1ac arch/arm64/kernel/traps.c:90 [<ffffffc000209e54>] show_stack+0x10/0x1c arch/arm64/kernel/traps.c:171 [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffc000f18dc4>] dump_stack+0x7c/0xd0 lib/dump_stack.c:50 [< inline >] print_address_description mm/kasan/report.c:147 [< inline >] kasan_report_error mm/kasan/report.c:236 [<ffffffc000373dcc>] kasan_report+0x380/0x4b8 mm/kasan/report.c:259 [< inline >] check_memory_region mm/kasan/kasan.c:264 [<ffffffc00037352c>] __asan_load8+0x20/0x70 mm/kasan/kasan.c:507 [<ffffffc0005b9624>] memcpy_fromiovec+0x5c/0x114 lib/iovec.c:15 [< inline >] memcpy_from_msg include/linux/skbuff.h:2667 [<ffffffc000ddeba0>] ping_common_sendmsg+0x50/0x108 net/ipv4/ping.c:674 [<ffffffc000dded30>] ping_v4_sendmsg+0xd8/0x698 net/ipv4/ping.c:714 [<ffffffc000dc91dc>] inet_sendmsg+0xe0/0x12c net/ipv4/af_inet.c:749 [< inline >] __sock_sendmsg_nosec net/socket.c:624 [< inline >] __sock_sendmsg net/socket.c:632 [<ffffffc000cab61c>] sock_sendmsg+0x124/0x164 net/socket.c:643 [< inline >] SYSC_sendto net/socket.c:1797 [<ffffffc000cad270>] SyS_sendto+0x178/0x1d8 net/socket.c:1761 CVE-2016-8399 Reported-by: Qidan He <i@flanker017.me> Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05net: bridge: set error code on failurePan Bian
Function br_sysfs_addbr() does not set error code when the call kobject_create_and_add() returns a NULL pointer. It may be better to return "-ENOMEM" when kobject_create_and_add() fails. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188781 Signed-off-by: Pan Bian <bianpan2016@163.com> Acked-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05net: af_mpls.c add space before open parenthesisSuraj Deshmukh
Adding space after switch keyword before open parenthesis for readability purpose. This patch fixes the checkpatch.pl warning: space required before the open parenthesis '(' Signed-off-by: Suraj Deshmukh <surajssd009005@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05ipv4: Drop suffix update from resize codeAlexander Duyck
It has been reported that update_suffix can be expensive when it is called on a large node in which most of the suffix lengths are the same. The time required to add 200K entries had increased from around 3 seconds to almost 49 seconds. In order to address this we need to move the code for updating the suffix out of resize and instead just have it handled in the cases where we are pushing a node that increases the suffix length, or will decrease the suffix length. Fixes: 5405afd1a306 ("fib_trie: Add tracking value for suffix length") Reported-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Reviewed-by: Robert Shearman <rshearma@brocade.com> Tested-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-05ipv4: Drop leaf from suffix pull/push functionsAlexander Duyck
It wasn't necessary to pass a leaf in when doing the suffix updates so just drop it. Instead just pass the suffix and work with that. Since we dropped the leaf there is no need to include that in the name so the names are updated to node_push_suffix and node_pull_suffix. Finally I noticed that the logic for pulling the suffix length back actually had some issues. Specifically it would stop prematurely if there was a longer suffix, but it was not as long as the original suffix. I updated the code to address that in node_pull_suffix. Fixes: 5405afd1a306 ("fib_trie: Add tracking value for suffix length") Suggested-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Reviewed-by: Robert Shearman <rshearma@brocade.com> Tested-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-03net: dcb: set error code on failuresPan Bian
In function dcbnl_cee_fill(), returns the value of variable err on errors. However, on some error paths (e.g. nla put fails), its value may be 0. It may be better to explicitly set a negative errno to variable err before returning. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188881 Signed-off-by: Pan Bian <bianpan2016@163.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-03Merge tag 'batadv-net-for-davem-20161202' of git://git.open-mesh.org/linux-mergeDavid S. Miller
Simon Wunderlich says: ==================== Here is another batman-adv bugfix: - fix checking for failed allocation of TVLV blocks in TT local data, by Sven Eckelmann ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02net: avoid signed overflows for SO_{SND|RCV}BUFFORCEEric Dumazet
CAP_NET_ADMIN users should not be allowed to set negative sk_sndbuf or sk_rcvbuf values, as it can lead to various memory corruptions, crashes, OOM... Note that before commit 82981930125a ("net: cleanups in sock_setsockopt()"), the bug was even more serious, since SO_SNDBUF and SO_RCVBUF were vulnerable. This needs to be backported to all known linux kernels. Again, many thanks to syzkaller team for discovering this gem. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02tipc: check minimum bearer MTUMichal Kubeček
Qian Zhang (张谦) reported a potential socket buffer overflow in tipc_msg_build() which is also known as CVE-2016-8632: due to insufficient checks, a buffer overflow can occur if MTU is too short for even tipc headers. As anyone can set device MTU in a user/net namespace, this issue can be abused by a regular user. As agreed in the discussion on Ben Hutchings' original patch, we should check the MTU at the moment a bearer is attached rather than for each processed packet. We also need to repeat the check when bearer MTU is adjusted to new device MTU. UDP case also needs a check to avoid overflow when calculating bearer MTU. Fixes: b97bf3fd8f6a ("[TIPC] Initial merge") Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Reported-by: Qian Zhang (张谦) <zhangqian-c@360.cn> Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02ip6_offload: check segs for NULL in ipv6_gso_segment.Artem Savkov
segs needs to be checked for being NULL in ipv6_gso_segment() before calling skb_shinfo(segs), otherwise kernel can run into a NULL-pointer dereference: [ 97.811262] BUG: unable to handle kernel NULL pointer dereference at 00000000000000cc [ 97.819112] IP: [<ffffffff816e52f9>] ipv6_gso_segment+0x119/0x2f0 [ 97.825214] PGD 0 [ 97.827047] [ 97.828540] Oops: 0000 [#1] SMP [ 97.831678] Modules linked in: vhost_net vhost macvtap macvlan nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter bridge stp llc snd_hda_codec_realtek snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel snd_hda_codec edac_mce_amd snd_hda_core edac_core snd_hwdep kvm_amd snd_seq kvm snd_seq_device snd_pcm irqbypass snd_timer ppdev parport_serial snd parport_pc k10temp pcspkr soundcore parport sp5100_tco shpchp sg wmi i2c_piix4 acpi_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sr_mod cdrom sd_mod ata_generic pata_acpi amdkfd amd_iommu_v2 radeon broadcom bcm_phy_lib i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm ahci serio_raw tg3 firewire_ohci libahci pata_atiixp drm ptp libata firewire_core pps_core i2c_core crc_itu_t fjes dm_mirror dm_region_hash dm_log dm_mod [ 97.927721] CPU: 1 PID: 3504 Comm: vhost-3495 Not tainted 4.9.0-7.el7.test.x86_64 #1 [ 97.935457] Hardware name: AMD Snook/Snook, BIOS ESK0726A 07/26/2010 [ 97.941806] task: ffff880129a1c080 task.stack: ffffc90001bcc000 [ 97.947720] RIP: 0010:[<ffffffff816e52f9>] [<ffffffff816e52f9>] ipv6_gso_segment+0x119/0x2f0 [ 97.956251] RSP: 0018:ffff88012fc43a10 EFLAGS: 00010207 [ 97.961557] RAX: 0000000000000000 RBX: ffff8801292c8700 RCX: 0000000000000594 [ 97.968687] RDX: 0000000000000593 RSI: ffff880129a846c0 RDI: 0000000000240000 [ 97.975814] RBP: ffff88012fc43a68 R08: ffff880129a8404e R09: 0000000000000000 [ 97.982942] R10: 0000000000000000 R11: ffff880129a84076 R12: 00000020002949b3 [ 97.990070] R13: ffff88012a580000 R14: 0000000000000000 R15: ffff88012a580000 [ 97.997198] FS: 0000000000000000(0000) GS:ffff88012fc40000(0000) knlGS:0000000000000000 [ 98.005280] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 98.011021] CR2: 00000000000000cc CR3: 0000000126c5d000 CR4: 00000000000006e0 [ 98.018149] Stack: [ 98.020157] 00000000ffffffff ffff88012fc43ac8 ffffffffa017ad0a 000000000000000e [ 98.027584] 0000001300000000 0000000077d59998 ffff8801292c8700 00000020002949b3 [ 98.035010] ffff88012a580000 0000000000000000 ffff88012a580000 ffff88012fc43a98 [ 98.042437] Call Trace: [ 98.044879] <IRQ> [ 98.046803] [<ffffffffa017ad0a>] ? tg3_start_xmit+0x84a/0xd60 [tg3] [ 98.053156] [<ffffffff815eeee0>] skb_mac_gso_segment+0xb0/0x130 [ 98.059158] [<ffffffff815eefd3>] __skb_gso_segment+0x73/0x110 [ 98.064985] [<ffffffff815ef40d>] validate_xmit_skb+0x12d/0x2b0 [ 98.070899] [<ffffffff815ef5d2>] validate_xmit_skb_list+0x42/0x70 [ 98.077073] [<ffffffff81618560>] sch_direct_xmit+0xd0/0x1b0 [ 98.082726] [<ffffffff815efd86>] __dev_queue_xmit+0x486/0x690 [ 98.088554] [<ffffffff8135c135>] ? cpumask_next_and+0x35/0x50 [ 98.094380] [<ffffffff815effa0>] dev_queue_xmit+0x10/0x20 [ 98.099863] [<ffffffffa09ce057>] br_dev_queue_push_xmit+0xa7/0x170 [bridge] [ 98.106907] [<ffffffffa09ce161>] br_forward_finish+0x41/0xc0 [bridge] [ 98.113430] [<ffffffff81627cf2>] ? nf_iterate+0x52/0x60 [ 98.118735] [<ffffffff81627d6b>] ? nf_hook_slow+0x6b/0xc0 [ 98.124216] [<ffffffffa09ce32c>] __br_forward+0x14c/0x1e0 [bridge] [ 98.130480] [<ffffffffa09ce120>] ? br_dev_queue_push_xmit+0x170/0x170 [bridge] [ 98.137785] [<ffffffffa09ce4bd>] br_forward+0x9d/0xb0 [bridge] [ 98.143701] [<ffffffffa09cfbb7>] br_handle_frame_finish+0x267/0x560 [bridge] [ 98.150834] [<ffffffffa09d0064>] br_handle_frame+0x174/0x2f0 [bridge] [ 98.157355] [<ffffffff8102fb89>] ? sched_clock+0x9/0x10 [ 98.162662] [<ffffffff810b63b2>] ? sched_clock_cpu+0x72/0xa0 [ 98.168403] [<ffffffff815eccf5>] __netif_receive_skb_core+0x1e5/0xa20 [ 98.174926] [<ffffffff813659f9>] ? timerqueue_add+0x59/0xb0 [ 98.180580] [<ffffffff815ed548>] __netif_receive_skb+0x18/0x60 [ 98.186494] [<ffffffff815ee625>] process_backlog+0x95/0x140 [ 98.192145] [<ffffffff815edccd>] net_rx_action+0x16d/0x380 [ 98.197713] [<ffffffff8170cff1>] __do_softirq+0xd1/0x283 [ 98.203106] [<ffffffff8170b2bc>] do_softirq_own_stack+0x1c/0x30 [ 98.209107] <EOI> [ 98.211029] [<ffffffff8108a5c0>] do_softirq+0x50/0x60 [ 98.216166] [<ffffffff815ec853>] netif_rx_ni+0x33/0x80 [ 98.221386] [<ffffffffa09eeff7>] tun_get_user+0x487/0x7f0 [tun] [ 98.227388] [<ffffffffa09ef3ab>] tun_sendmsg+0x4b/0x60 [tun] [ 98.233129] [<ffffffffa0b68932>] handle_tx+0x282/0x540 [vhost_net] [ 98.239392] [<ffffffffa0b68c25>] handle_tx_kick+0x15/0x20 [vhost_net] [ 98.245916] [<ffffffffa0abacfe>] vhost_worker+0x9e/0xf0 [vhost] [ 98.251919] [<ffffffffa0abac60>] ? vhost_umem_alloc+0x40/0x40 [vhost] [ 98.258440] [<ffffffff81003a47>] ? do_syscall_64+0x67/0x180 [ 98.264094] [<ffffffff810a44d9>] kthread+0xd9/0xf0 [ 98.268965] [<ffffffff810a4400>] ? kthread_park+0x60/0x60 [ 98.274444] [<ffffffff8170a4d5>] ret_from_fork+0x25/0x30 [ 98.279836] Code: 8b 93 d8 00 00 00 48 2b 93 d0 00 00 00 4c 89 e6 48 89 df 66 89 93 c2 00 00 00 ff 10 48 3d 00 f0 ff ff 49 89 c2 0f 87 52 01 00 00 <41> 8b 92 cc 00 00 00 48 8b 80 d0 00 00 00 44 0f b7 74 10 06 66 [ 98.299425] RIP [<ffffffff816e52f9>] ipv6_gso_segment+0x119/0x2f0 [ 98.305612] RSP <ffff88012fc43a10> [ 98.309094] CR2: 00000000000000cc [ 98.312406] ---[ end trace 726a2c7a2d2d78d0 ]--- Signed-off-by: Artem Savkov <asavkov@redhat.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02RDS: TCP: unregister_netdevice_notifier() in error path of rds_tcp_init_netSowmini Varadhan
If some error is encountered in rds_tcp_init_net, make sure to unregister_netdevice_notifier(), else we could trigger a panic later on, when the modprobe from a netns fails. Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02Revert: "ip6_tunnel: Update skb->protocol to ETH_P_IPV6 in ip6_tnl_xmit()"Eli Cooper
This reverts commit ae148b085876fa771d9ef2c05f85d4b4bf09ce0d ("ip6_tunnel: Update skb->protocol to ETH_P_IPV6 in ip6_tnl_xmit()"). skb->protocol is now set in __ip_local_out() and __ip6_local_out() before dst_output() is called. It is no longer necessary to do it for each tunnel. Cc: stable@vger.kernel.org Signed-off-by: Eli Cooper <elicooper@gmx.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02ipv6: Set skb->protocol properly for local outputEli Cooper
When xfrm is applied to TSO/GSO packets, it follows this path: xfrm_output() -> xfrm_output_gso() -> skb_gso_segment() where skb_gso_segment() relies on skb->protocol to function properly. This patch sets skb->protocol to ETH_P_IPV6 before dst_output() is called, fixing a bug where GSO packets sent through an ipip6 tunnel are dropped when xfrm is involved. Cc: stable@vger.kernel.org Signed-off-by: Eli Cooper <elicooper@gmx.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02ipv4: Set skb->protocol properly for local outputEli Cooper
When xfrm is applied to TSO/GSO packets, it follows this path: xfrm_output() -> xfrm_output_gso() -> skb_gso_segment() where skb_gso_segment() relies on skb->protocol to function properly. This patch sets skb->protocol to ETH_P_IP before dst_output() is called, fixing a bug where GSO packets sent through a sit tunnel are dropped when xfrm is involved. Cc: stable@vger.kernel.org Signed-off-by: Eli Cooper <elicooper@gmx.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02packet: fix race condition in packet_set_ringPhilip Pettersson
When packet_set_ring creates a ring buffer it will initialize a struct timer_list if the packet version is TPACKET_V3. This value can then be raced by a different thread calling setsockopt to set the version to TPACKET_V1 before packet_set_ring has finished. This leads to a use-after-free on a function pointer in the struct timer_list when the socket is closed as the previously initialized timer will not be deleted. The bug is fixed by taking lock_sock(sk) in packet_setsockopt when changing the packet version while also taking the lock at the start of packet_set_ring. Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.") Signed-off-by: Philip Pettersson <philip.pettersson@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02net/rtnetlink: fix attribute name in nlmsg_size() commentsTobias Klauser
Use the correct attribute constant names IFLA_GSO_MAX_{SEGS,SIZE} instead of IFLA_MAX_GSO_{SEGS,SIZE} for the comments int nlmsg_size(). Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02batman-adv: Check for alloc errors when preparing TT local dataSven Eckelmann
batadv_tt_prepare_tvlv_local_data can fail to allocate the memory for the new TVLV block. The caller is informed about this problem with the returned length of 0. Not checking this value results in an invalid memory access when either tt_data or tt_change is accessed. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific") Signed-off-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
2016-12-01Merge branch 'master' of ↵David S. Miller
git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec Steffen Klassert says: ==================== pull request (net): ipsec 2016-12-01 1) Change the error value when someone tries to run 32bit userspace on a 64bit host from -ENOTSUPP to the userspace exported -EOPNOTSUPP. Fix from Yi Zhao. 2) On inbound, ESN sequence numbers are already in network byte order. So don't try to convert it again, this fixes integrity verification for ESN. Fixes from Tobias Brunner. Please pull or let me know if there are problems. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-01Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nfDavid S. Miller
Pablo Neira Ayuso says: ==================== Netfilter fixes for net This is a large batch of Netfilter fixes for net, they are: 1) Three patches to fix NAT conversion to rhashtable: Switch to rhlist structure that allows to have several objects with the same key. Moreover, fix wrong comparison logic in nf_nat_bysource_cmp() as this is expecting a return value similar to memcmp(). Change location of the nat_bysource field in the nf_conn structure to avoid zeroing this as it breaks interaction with SLAB_DESTROY_BY_RCU and lead us to crashes. From Florian Westphal. 2) Don't allow malformed fragments go through in IPv6, drop them, otherwise we hit GPF, patch from Florian Westphal. 3) Fix crash if attributes are missing in nft_range, from Liping Zhang. 4) Fix arptables 32-bits userspace 64-bits kernel compat, from Hongxu Jia. 5) Two patches from David Ahern to fix netfilter interaction with vrf. From David Ahern. 6) Fix element timeout calculation in nf_tables, we take milliseconds from userspace, but we use jiffies from kernelspace. Patch from Anders K. Pedersen. 7) Missing validation length netlink attribute for nft_hash, from Laura Garcia. 8) Fix nf_conntrack_helper documentation, we don't default to off anymore for a bit of time so let's get this in sync with the code. I know is late but I think these are important, specifically the NAT bits, as they are mostly addressing fallout from recent changes. I also read there are chances to have -rc8, if that is the case, that would also give us a bit more time to test this. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30netfilter: arp_tables: fix invoking 32bit "iptable -P INPUT ACCEPT" failed ↵Hongxu Jia
in 64bit kernel Since 09d9686047db ("netfilter: x_tables: do compat validation via translate_table"), it used compatr structure to assign newinfo structure. In translate_compat_table of ip_tables.c and ip6_tables.c, it used compatr->hook_entry to replace info->hook_entry and compatr->underflow to replace info->underflow, but not do the same replacement in arp_tables.c. It caused invoking 32-bit "arptbale -P INPUT ACCEPT" failed in 64bit kernel. -------------------------------------- root@qemux86-64:~# arptables -P INPUT ACCEPT root@qemux86-64:~# arptables -P INPUT ACCEPT ERROR: Policy for `INPUT' offset 448 != underflow 0 arptables: Incompatible with this kernel -------------------------------------- Fixes: 09d9686047db ("netfilter: x_tables: do compat validation via translate_table") Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2016-11-30l2tp: fix address test in __l2tp_ip6_bind_lookup()Guillaume Nault
The '!(addr && ipv6_addr_equal(addr, laddr))' part of the conditional matches if addr is NULL or if addr != laddr. But the intend of __l2tp_ip6_bind_lookup() is to find a sockets with the same address, so the ipv6_addr_equal() condition needs to be inverted. For better clarity and consistency with the rest of the expression, the (!X || X == Y) notation is used instead of !(X && X != Y). Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30l2tp: fix lookup for sockets not bound to a device in l2tp_ipGuillaume Nault
When looking up an l2tp socket, we must consider a null netdevice id as wild card. There are currently two problems caused by __l2tp_ip_bind_lookup() not considering 'dif' as wild card when set to 0: * A socket bound to a device (i.e. with sk->sk_bound_dev_if != 0) never receives any packet. Since __l2tp_ip_bind_lookup() is called with dif == 0 in l2tp_ip_recv(), sk->sk_bound_dev_if is always different from 'dif' so the socket doesn't match. * Two sockets, one bound to a device but not the other, can be bound to the same address. If the first socket binding to the address is the one that is also bound to a device, the second socket can bind to the same address without __l2tp_ip_bind_lookup() noticing the overlap. To fix this issue, we need to consider that any null device index, be it 'sk->sk_bound_dev_if' or 'dif', matches with any other value. We also need to pass the input device index to __l2tp_ip_bind_lookup() on reception so that sockets bound to a device never receive packets from other devices. This patch fixes l2tp_ip6 in the same way. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30l2tp: fix racy socket lookup in l2tp_ip and l2tp_ip6 bind()Guillaume Nault
It's not enough to check for sockets bound to same address at the beginning of l2tp_ip{,6}_bind(): even if no socket is found at that time, a socket with the same address could be bound before we take the l2tp lock again. This patch moves the lookup right before inserting the new socket, so that no change can ever happen to the list between address lookup and socket insertion. Care is taken to avoid side effects on the socket in case of failure. That is, modifications of the socket are done after the lookup, when binding is guaranteed to succeed, and before releasing the l2tp lock, so that concurrent lookups will always see fully initialised sockets. For l2tp_ip, 'ret' is set to -EINVAL before checking the SOCK_ZAPPED bit. Error code was mistakenly set to -EADDRINUSE on error by commit 32c231164b76 ("l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{,6}_bind()"). Using -EINVAL restores original behaviour. For l2tp_ip6, the lookup is now always done with the correct bound device. Before this patch, when binding to a link-local address, the lookup was done with the original sk->sk_bound_dev_if, which was later overwritten with addr->l2tp_scope_id. Lookup is now performed with the final sk->sk_bound_dev_if value. Finally, the (addr_len >= sizeof(struct sockaddr_in6)) check has been dropped: addr is a sockaddr_l2tpip6 not sockaddr_in6 and addr_len has already been checked at this point (this part of the code seems to have been copy-pasted from net/ipv6/raw.c). Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30l2tp: hold socket before dropping lock in l2tp_ip{, 6}_recv()Guillaume Nault
Socket must be held while under the protection of the l2tp lock; there is no guarantee that sk remains valid after the read_unlock_bh() call. Same issue for l2tp_ip and l2tp_ip6. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30l2tp: lock socket before checking flags in connect()Guillaume Nault
Socket flags aren't updated atomically, so the socket must be locked while reading the SOCK_ZAPPED flag. This issue exists for both l2tp_ip and l2tp_ip6. For IPv6, this patch also brings error handling for __ip6_datagram_connect() failures. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30openvswitch: Fix skb leak in IPv6 reassembly.Daniele Di Proietto
If nf_ct_frag6_gather() returns an error other than -EINPROGRESS, it means that we still have a reference to the skb. We should free it before returning from handle_fragments, as stated in the comment above. Fixes: daaa7d647f81 ("netfilter: ipv6: avoid nf_iterate recursion") CC: Florian Westphal <fw@strlen.de> CC: Pravin B Shelar <pshelar@ovn.org> CC: Joe Stringer <joe@ovn.org> Signed-off-by: Daniele Di Proietto <diproiettod@ovn.org> Acked-by: Pravin B Shelar <pshelar@ovn.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-30esp6: Fix integrity verification when ESN are usedTobias Brunner
When handling inbound packets, the two halves of the sequence number stored on the skb are already in network order. Fixes: 000ae7b2690e ("esp6: Switch to new AEAD interface") Signed-off-by: Tobias Brunner <tobias@strongswan.org> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2016-11-30esp4: Fix integrity verification when ESN are usedTobias Brunner
When handling inbound packets, the two halves of the sequence number stored on the skb are already in network order. Fixes: 7021b2e1cddd ("esp4: Switch to new AEAD interface") Signed-off-by: Tobias Brunner <tobias@strongswan.org> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2016-11-30xfrm_user: fix return value from xfrm_user_rcv_msgYi Zhao
It doesn't support to run 32bit 'ip' to set xfrm objdect on 64bit host. But the return value is unknown for user program: ip xfrm policy list RTNETLINK answers: Unknown error 524 Replace ENOTSUPP with EOPNOTSUPP: ip xfrm policy list RTNETLINK answers: Operation not supported Signed-off-by: Yi Zhao <yi.zhao@windriver.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2016-11-29net: dsa: slave: fix fixed-link phydev leaksJohan Hovold
Make sure to deregister and free any fixed-link PHY registered using of_phy_register_fixed_link() on slave-setup errors and on slave destroy. Fixes: 0d8bcdd383b8 ("net: dsa: allow for more complex PHY setups") Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29of_mdio: add helper to deregister fixed-link PHYsJohan Hovold
Add helper to deregister fixed-link PHYs registered using of_phy_register_fixed_link(). Convert the two drivers that care to deregister their fixed-link PHYs to use the new helper, but note that most drivers currently fail to do so. Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29net: dsa: slave: fix of-node leak and phy priorityJohan Hovold
Make sure to drop the reference taken by of_parse_phandle() before returning from dsa_slave_phy_setup(). Note that this also modifies the PHY priority so that any fixed-link node is only parsed when no phy-handle is given, which is in accordance with the common scheme for this. Fixes: 0d8bcdd383b8 ("net: dsa: allow for more complex PHY setups") Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29GSO: Reload iph after pskb_may_pullArnaldo Carvalho de Melo
As it may get stale and lead to use after free. Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Alexander Duyck <aduyck@mirantis.com> Cc: Andrey Konovalov <andreyknvl@google.com> Fixes: cbc53e08a793 ("GSO: Add GSO type for fixed IPv4 ID") Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29sched: cls_flower: remove from hashtable only in case skip sw flag is not setJiri Pirko
Be symmetric to hashtable insert and remove filter from hashtable only in case skip sw flag is not set. Fixes: e69985c67c33 ("net/sched: cls_flower: Introduce support in SKIP SW flag") Signed-off-by: Jiri Pirko <jiri@mellanox.com> Reviewed-by: Amir Vadai <amir@vadai.me> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29net/dccp: fix use-after-free in dccp_invalid_packetEric Dumazet
pskb_may_pull() can reallocate skb->head, we need to reload dh pointer in dccp_invalid_packet() or risk use after free. Bug found by Andrey Konovalov using syzkaller. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29netlink: Call cb->done from a worker threadHerbert Xu
The cb->done interface expects to be called in process context. This was broken by the netlink RCU conversion. This patch fixes it by adding a worker struct to make the cb->done call where necessary. Fixes: 21e4902aea80 ("netlink: Lockless lookup with RCU grace...") Reported-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29net/sched: pedit: make sure that offset is validAmir Vadai
Add a validation function to make sure offset is valid: 1. Not below skb head (could happen when offset is negative). 2. Validate both 'offset' and 'at'. Signed-off-by: Amir Vadai <amir@vadai.me> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29netfilter: ipv6: nf_defrag: drop mangled skb on ream errorFlorian Westphal
Dmitry Vyukov reported GPF in network stack that Andrey traced down to negative nh offset in nf_ct_frag6_queue(). Problem is that all network headers before fragment header are pulled. Normal ipv6 reassembly will drop the skb when errors occur further down the line. netfilter doesn't do this, and instead passed the original fragment along. That was also fine back when netfilter ipv6 defrag worked with cloned fragments, as the original, pristine fragment was passed on. So we either have to undo the pull op, or discard such fragments. Since they're malformed after all (e.g. overlapping fragment) it seems preferrable to just drop them. Same for temporary errors -- it doesn't make sense to accept (and perhaps forward!) only some fragments of same datagram. Fixes: 029f7f3b8701cc7ac ("netfilter: ipv6: nf_defrag: avoid/free clone operations") Reported-by: Dmitry Vyukov <dvyukov@google.com> Debugged-by: Andrey Konovalov <andreyknvl@google.com> Diagnosed-by: Eric Dumazet <Eric Dumazet <edumazet@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2016-11-28net: dsa: fix unbalanced dsa_switch_tree reference countingNikita Yushchenko
_dsa_register_switch() gets a dsa_switch_tree object either via dsa_get_dst() or via dsa_add_dst(). Former path does not increase kref in returned object (resulting into caller not owning a reference), while later path does create a new object (resulting into caller owning a reference). The rest of _dsa_register_switch() assumes that it owns a reference, and calls dsa_put_dst(). This causes a memory breakage if first switch in the tree initialized successfully, but second failed to initialize. In particular, freed dsa_swith_tree object is left referenced by switch that was initialized, and later access to sysfs attributes of that switch cause OOPS. To fix, need to add kref_get() call to dsa_get_dst(). Fixes: 83c0afaec7b7 ("net: dsa: Add new binding implementation") Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-28net: handle no dst on skb in icmp6_sendDavid Ahern
Andrey reported the following while fuzzing the kernel with syzkaller: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Modules linked in: CPU: 0 PID: 3859 Comm: a.out Not tainted 4.9.0-rc6+ #429 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff8800666d4200 task.stack: ffff880067348000 RIP: 0010:[<ffffffff833617ec>] [<ffffffff833617ec>] icmp6_send+0x5fc/0x1e30 net/ipv6/icmp.c:451 RSP: 0018:ffff88006734f2c0 EFLAGS: 00010206 RAX: ffff8800666d4200 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: dffffc0000000000 RDI: 0000000000000018 RBP: ffff88006734f630 R08: ffff880064138418 R09: 0000000000000003 R10: dffffc0000000000 R11: 0000000000000005 R12: 0000000000000000 R13: ffffffff84e7e200 R14: ffff880064138484 R15: ffff8800641383c0 FS: 00007fb3887a07c0(0000) GS:ffff88006cc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000000 CR3: 000000006b040000 CR4: 00000000000006f0 Stack: ffff8800666d4200 ffff8800666d49f8 ffff8800666d4200 ffffffff84c02460 ffff8800666d4a1a 1ffff1000ccdaa2f ffff88006734f498 0000000000000046 ffff88006734f440 ffffffff832f4269 ffff880064ba7456 0000000000000000 Call Trace: [<ffffffff83364ddc>] icmpv6_param_prob+0x2c/0x40 net/ipv6/icmp.c:557 [< inline >] ip6_tlvopt_unknown net/ipv6/exthdrs.c:88 [<ffffffff83394405>] ip6_parse_tlv+0x555/0x670 net/ipv6/exthdrs.c:157 [<ffffffff8339a759>] ipv6_parse_hopopts+0x199/0x460 net/ipv6/exthdrs.c:663 [<ffffffff832ee773>] ipv6_rcv+0xfa3/0x1dc0 net/ipv6/ip6_input.c:191 ... icmp6_send / icmpv6_send is invoked for both rx and tx paths. In both cases the dst->dev should be preferred for determining the L3 domain if the dst has been set on the skb. Fallback to the skb->dev if it has not. This covers the case reported here where icmp6_send is invoked on Rx before the route lookup. Fixes: 5d41ce29e ("net: icmp6_send should use dst dev to determine L3 domain") Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-28tcp: Set DEFAULT_TCP_CONG to bbr if DEFAULT_BBR is setJulian Wollrath
Signed-off-by: Julian Wollrath <jwollrath@web.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-28net, sched: respect rcu grace period on cls destructionDaniel Borkmann
Roi reported a crash in flower where tp->root was NULL in ->classify() callbacks. Reason is that in ->destroy() tp->root is set to NULL via RCU_INIT_POINTER(). It's problematic for some of the classifiers, because this doesn't respect RCU grace period for them, and as a result, still outstanding readers from tc_classify() will try to blindly dereference a NULL tp->root. The tp->root object is strictly private to the classifier implementation and holds internal data the core such as tc_ctl_tfilter() doesn't know about. Within some classifiers, such as cls_bpf, cls_basic, etc, tp->root is only checked for NULL in ->get() callback, but nowhere else. This is misleading and seemed to be copied from old classifier code that was not cleaned up properly. For example, d3fa76ee6b4a ("[NET_SCHED]: cls_basic: fix NULL pointer dereference") moved tp->root initialization into ->init() routine, where before it was part of ->change(), so ->get() had to deal with tp->root being NULL back then, so that was indeed a valid case, after d3fa76ee6b4a, not really anymore. We used to set tp->root to NULL long ago in ->destroy(), see 47a1a1d4be29 ("pkt_sched: remove unnecessary xchg() in packet classifiers"); but the NULLifying was reintroduced with the RCUification, but it's not correct for every classifier implementation. In the cases that are fixed here with one exception of cls_cgroup, tp->root object is allocated and initialized inside ->init() callback, which is always performed at a point in time after we allocate a new tp, which means tp and thus tp->root was not globally visible in the tp chain yet (see tc_ctl_tfilter()). Also, on destruction tp->root is strictly kfree_rcu()'ed in ->destroy() handler, same for the tp which is kfree_rcu()'ed right when we return from ->destroy() in tcf_destroy(). This means, the head object's lifetime for such classifiers is always tied to the tp lifetime. The RCU callback invocation for the two kfree_rcu() could be out of order, but that's fine since both are independent. Dropping the RCU_INIT_POINTER(tp->root, NULL) for these classifiers here means that 1) we don't need a useless NULL check in fast-path and, 2) that outstanding readers of that tp in tc_classify() can still execute under respect with RCU grace period as it is actually expected. Things that haven't been touched here: cls_fw and cls_route. They each handle tp->root being NULL in ->classify() path for historic reasons, so their ->destroy() implementation can stay as is. If someone actually cares, they could get cleaned up at some point to avoid the test in fast path. cls_u32 doesn't set tp->root to NULL. For cls_rsvp, I just added a !head should anyone actually be using/testing it, so it at least aligns with cls_fw and cls_route. For cls_flower we additionally need to defer rhashtable destruction (to a sleepable context) after RCU grace period as concurrent readers might still access it. (Note that in this case we need to hold module reference to keep work callback address intact, since we only wait on module unload for all call_rcu()s to finish.) This fixes one race to bring RCU grace period guarantees back. Next step as worked on by Cong however is to fix 1e052be69d04 ("net_sched: destroy proto tp when all filters are gone") to get the order of unlinking the tp in tc_ctl_tfilter() for the RTM_DELTFILTER case right by moving RCU_INIT_POINTER() before tcf_destroy() and let the notification for removal be done through the prior ->delete() callback. Both are independant issues. Once we have that right, we can then clean tp->root up for a number of classifiers by not making them RCU pointers, which requires a new callback (->uninit) that is triggered from tp's RCU callback, where we just kfree() tp->root from there. Fixes: 1f947bf151e9 ("net: sched: rcu'ify cls_bpf") Fixes: 9888faefe132 ("net: sched: cls_basic use RCU") Fixes: 70da9f0bf999 ("net: sched: cls_flow use RCU") Fixes: 77b9900ef53a ("tc: introduce Flower classifier") Fixes: bf3994d2ed31 ("net/sched: introduce Match-all classifier") Fixes: 952313bd6258 ("net: sched: cls_cgroup use RCU") Reported-by: Roi Dayan <roid@mellanox.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Roi Dayan <roid@mellanox.com> Cc: Jiri Pirko <jiri@mellanox.com> Acked-by: John Fastabend <john.r.fastabend@intel.com> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-27tipc: fix link statistics counter errorsJon Paul Maloy
In commit e4bf4f76962b ("tipc: simplify packet sequence number handling") we changed the internal representation of the packet sequence number counters from u32 to u16, reflecting what is really sent over the wire. Since then some link statistics counters have been displaying incorrect values, partially because the counters meant to be used as sequence number snapshots are now used as direct counters, stored as u32, and partially because some counter updates are just missing in the code. In this commit we correct this in two ways. First, we base the displayed packet sent/received values on direct counters instead of as previously a calculated difference between current sequence number and a snapshot. Second, we add the missing updates of the counters. This change is compatible with the current netlink API, and requires no changes to the user space tools. Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-27Merge branch 'master' of ↵David S. Miller
git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec Steffen Klassert says: ==================== pull request (net): ipsec 2016-11-25 1) Fix a refcount leak in vti6. From Nicolas Dichtel. 2) Fix a wrong if statement in xfrm_sk_policy_lookup. From Florian Westphal. 3) The flowcache watermarks are per cpu. Take this into account when comparing to the threshold where we refusing new allocations. From Miroslav Urbanek. Please pull or let me know if there are problems. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-27net: dsa: fix fixed-link-phy device leaksJohan Hovold
Make sure to drop the reference taken by of_phy_find_device() when registering and deregistering the fixed-link PHY-device. Fixes: 39b0c705195e ("net: dsa: Allow configuration of CPU & DSA port speeds/duplex") Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-25tipc: resolve connection flow control compatibility problemJon Paul Maloy
In commit 10724cc7bb78 ("tipc: redesign connection-level flow control") we replaced the previous message based flow control with one based on 1k blocks. In order to ensure backwards compatibility the mechanism falls back to using message as base unit when it senses that the peer doesn't support the new algorithm. The default flow control window, i.e., how many units can be sent before the sender blocks and waits for an acknowledge (aka advertisement) is 512. This was tested against the previous version, which uses an acknowledge frequency of on ack per 256 received message, and found to work fine. However, we missed the fact that versions older than Linux 3.15 use an acknowledge frequency of 512, which is exactly the limit where a 4.6+ sender will stop and wait for acknowledge. This would also work fine if it weren't for the fact that if the first sent message on a 4.6+ server side is an empty SYNACK, this one is also is counted as a sent message, while it is not counted as a received message on a legacy 3.15-receiver. This leads to the sender always being one step ahead of the receiver, a scenario causing the sender to block after 512 sent messages, while the receiver only has registered 511 read messages. Hence, the legacy receiver is not trigged to send an acknowledge, with a permanently blocked sender as result. We solve this deadlock by simply allowing the sender to send one more message before it blocks, i.e., by a making minimal change to the condition used for determining connection congestion. Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>