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authorEric Dumazet <edumazet@google.com>2020-01-06 12:30:48 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-01-12 12:21:46 +0100
commit74165c1ca31d58c1749bda5726661bd817eaa7d1 (patch)
tree6a5240fbd5d7e125887f21ab32990dc04eb1407f
parentae026afaf5e68885ca3a2d95bbab0b289eba088d (diff)
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macvlan: do not assume mac_header is set in macvlan_broadcast()
[ Upstream commit 96cc4b69581db68efc9749ef32e9cf8e0160c509 ] Use of eth_hdr() in tx path is error prone. Many drivers call skb_reset_mac_header() before using it, but others do not. Commit 6d1ccff62780 ("net: reset mac header in dev_start_xmit()") attempted to fix this generically, but commit d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option") brought back the macvlan bug. Lets add a new helper, so that tx paths no longer have to call skb_reset_mac_header() only to get a pointer to skb->data. Hopefully we will be able to revert 6d1ccff62780 ("net: reset mac header in dev_start_xmit()") and save few cycles in transmit fast path. BUG: KASAN: use-after-free in __get_unaligned_cpu32 include/linux/unaligned/packed_struct.h:19 [inline] BUG: KASAN: use-after-free in mc_hash drivers/net/macvlan.c:251 [inline] BUG: KASAN: use-after-free in macvlan_broadcast+0x547/0x620 drivers/net/macvlan.c:277 Read of size 4 at addr ffff8880a4932401 by task syz-executor947/9579 CPU: 0 PID: 9579 Comm: syz-executor947 Not tainted 5.5.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:639 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:145 __get_unaligned_cpu32 include/linux/unaligned/packed_struct.h:19 [inline] mc_hash drivers/net/macvlan.c:251 [inline] macvlan_broadcast+0x547/0x620 drivers/net/macvlan.c:277 macvlan_queue_xmit drivers/net/macvlan.c:520 [inline] macvlan_start_xmit+0x402/0x77f drivers/net/macvlan.c:559 __netdev_start_xmit include/linux/netdevice.h:4447 [inline] netdev_start_xmit include/linux/netdevice.h:4461 [inline] dev_direct_xmit+0x419/0x630 net/core/dev.c:4079 packet_direct_xmit+0x1a9/0x250 net/packet/af_packet.c:240 packet_snd net/packet/af_packet.c:2966 [inline] packet_sendmsg+0x260d/0x6220 net/packet/af_packet.c:2991 sock_sendmsg_nosec net/socket.c:639 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:659 __sys_sendto+0x262/0x380 net/socket.c:1985 __do_sys_sendto net/socket.c:1997 [inline] __se_sys_sendto net/socket.c:1993 [inline] __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1993 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x442639 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b 10 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc13549e08 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000442639 RDX: 000000000000000e RSI: 0000000020000080 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000403bb0 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 9389: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x163/0x770 mm/slab.c:3665 kmalloc include/linux/slab.h:561 [inline] tomoyo_realpath_from_path+0xc5/0x660 security/tomoyo/realpath.c:252 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_perm+0x230/0x430 security/tomoyo/file.c:822 tomoyo_inode_getattr+0x1d/0x30 security/tomoyo/tomoyo.c:129 security_inode_getattr+0xf2/0x150 security/security.c:1222 vfs_getattr+0x25/0x70 fs/stat.c:115 vfs_statx_fd+0x71/0xc0 fs/stat.c:145 vfs_fstat include/linux/fs.h:3265 [inline] __do_sys_newfstat+0x9b/0x120 fs/stat.c:378 __se_sys_newfstat fs/stat.c:375 [inline] __x64_sys_newfstat+0x54/0x80 fs/stat.c:375 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9389: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:335 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 tomoyo_realpath_from_path+0x1a7/0x660 security/tomoyo/realpath.c:289 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_perm+0x230/0x430 security/tomoyo/file.c:822 tomoyo_inode_getattr+0x1d/0x30 security/tomoyo/tomoyo.c:129 security_inode_getattr+0xf2/0x150 security/security.c:1222 vfs_getattr+0x25/0x70 fs/stat.c:115 vfs_statx_fd+0x71/0xc0 fs/stat.c:145 vfs_fstat include/linux/fs.h:3265 [inline] __do_sys_newfstat+0x9b/0x120 fs/stat.c:378 __se_sys_newfstat fs/stat.c:375 [inline] __x64_sys_newfstat+0x54/0x80 fs/stat.c:375 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a4932000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 1025 bytes inside of 4096-byte region [ffff8880a4932000, ffff8880a4933000) The buggy address belongs to the page: page:ffffea0002924c80 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0 raw: 00fffe0000010200 ffffea0002846208 ffffea00028f3888 ffff8880aa402000 raw: 0000000000000000 ffff8880a4932000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a4932300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a4932380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a4932400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a4932480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a4932500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Fixes: b863ceb7ddce ("[NET]: Add macvlan driver") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/net/macvlan.c2
-rw-r--r--include/linux/if_ether.h8
2 files changed, 9 insertions, 1 deletions
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 05631d97eeb4..747c0542a53c 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -259,7 +259,7 @@ static void macvlan_broadcast(struct sk_buff *skb,
struct net_device *src,
enum macvlan_mode mode)
{
- const struct ethhdr *eth = eth_hdr(skb);
+ const struct ethhdr *eth = skb_eth_hdr(skb);
const struct macvlan_dev *vlan;
struct sk_buff *nskb;
unsigned int i;
diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
index 76cf11e905e1..8a9792a6427a 100644
--- a/include/linux/if_ether.h
+++ b/include/linux/if_ether.h
@@ -24,6 +24,14 @@ static inline struct ethhdr *eth_hdr(const struct sk_buff *skb)
return (struct ethhdr *)skb_mac_header(skb);
}
+/* Prefer this version in TX path, instead of
+ * skb_reset_mac_header() + eth_hdr()
+ */
+static inline struct ethhdr *skb_eth_hdr(const struct sk_buff *skb)
+{
+ return (struct ethhdr *)skb->data;
+}
+
static inline struct ethhdr *inner_eth_hdr(const struct sk_buff *skb)
{
return (struct ethhdr *)skb_inner_mac_header(skb);