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2019-05-25cifs: fix strcat buffer overflow and reduce raciness in smb21_set_oplock_level()Christoph Probst
commit 6a54b2e002c9d00b398d35724c79f9fe0d9b38fb upstream. Change strcat to strncpy in the "None" case to fix a buffer overflow when cinode->oplock is reset to 0 by another thread accessing the same cinode. It is never valid to append "None" to any other message. Consolidate multiple writes to cinode->oplock to reduce raciness. Signed-off-by: Christoph Probst <kernel@probst.it> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-02cifs: do not attempt cifs operation on smb2+ rename errorFrank Sorenson
commit 652727bbe1b17993636346716ae5867627793647 upstream. A path-based rename returning EBUSY will incorrectly try opening the file with a cifs (NT Create AndX) operation on an smb2+ mount, which causes the server to force a session close. If the mount is smb2+, skip the fallback. Signed-off-by: Frank Sorenson <sorenson@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-02cifs: fix page reference leak with readv/writevJérôme Glisse
commit 13f5938d8264b5501368523c4513ff26608a33e8 upstream. CIFS can leak pages reference gotten through GUP (get_user_pages*() through iov_iter_get_pages()). This happen if cifs_send_async_read() or cifs_write_from_iter() calls fail from within __cifs_readv() and __cifs_writev() respectively. This patch move page unreference to cifs_aio_ctx_release() which will happens on all code paths this is all simpler to follow for correctness. Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Steve French <sfrench@samba.org> Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Stable <stable@vger.kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-02cifs: fix memory leak in SMB2_readRonnie Sahlberg
[ Upstream commit 05fd5c2c61732152a6bddc318aae62d7e436629b ] Commit 088aaf17aa79300cab14dbee2569c58cfafd7d6e introduced a leak where if SMB2_read() returned an error we would return without freeing the request buffer. Cc: Stable <stable@vger.kernel.org> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-27cifs: fix handle leak in smb2_query_symlink()Ronnie Sahlberg
commit e6d0fb7b34f264f72c33053558a360a6a734905e upstream. If we enter smb2_query_symlink() for something that is not a symlink and where the SMB2_open() would succeed we would never end up closing this handle and would thus leak a handle on the server. Fix this by immediately calling SMB2_close() on successfull open. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-27cifs: Fix use-after-free in SMB2_readZhangXiaoxu
commit 088aaf17aa79300cab14dbee2569c58cfafd7d6e upstream. There is a KASAN use-after-free: BUG: KASAN: use-after-free in SMB2_read+0x1136/0x1190 Read of size 8 at addr ffff8880b4e45e50 by task ln/1009 Should not release the 'req' because it will use in the trace. Fixes: eccb4422cf97 ("smb3: Add ftrace tracepoints for improved SMB3 debugging") Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org> 4.18+ Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-27cifs: Fix use-after-free in SMB2_writeZhangXiaoxu
commit 6a3eb3360667170988f8a6477f6686242061488a upstream. There is a KASAN use-after-free: BUG: KASAN: use-after-free in SMB2_write+0x1342/0x1580 Read of size 8 at addr ffff8880b6a8e450 by task ln/4196 Should not release the 'req' because it will use in the trace. Fixes: eccb4422cf97 ("smb3: Add ftrace tracepoints for improved SMB3 debugging") Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org> 4.18+ Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-27cifs: Fix lease buffer length errorZhangXiaoxu
commit b57a55e2200ede754e4dc9cce4ba9402544b9365 upstream. There is a KASAN slab-out-of-bounds: BUG: KASAN: slab-out-of-bounds in _copy_from_iter_full+0x783/0xaa0 Read of size 80 at addr ffff88810c35e180 by task mount.cifs/539 CPU: 1 PID: 539 Comm: mount.cifs Not tainted 4.19 #10 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0xdd/0x12a print_address_description+0xa7/0x540 kasan_report+0x1ff/0x550 check_memory_region+0x2f1/0x310 memcpy+0x2f/0x80 _copy_from_iter_full+0x783/0xaa0 tcp_sendmsg_locked+0x1840/0x4140 tcp_sendmsg+0x37/0x60 inet_sendmsg+0x18c/0x490 sock_sendmsg+0xae/0x130 smb_send_kvec+0x29c/0x520 __smb_send_rqst+0x3ef/0xc60 smb_send_rqst+0x25a/0x2e0 compound_send_recv+0x9e8/0x2af0 cifs_send_recv+0x24/0x30 SMB2_open+0x35e/0x1620 open_shroot+0x27b/0x490 smb2_open_op_close+0x4e1/0x590 smb2_query_path_info+0x2ac/0x650 cifs_get_inode_info+0x1058/0x28f0 cifs_root_iget+0x3bb/0xf80 cifs_smb3_do_mount+0xe00/0x14c0 cifs_do_mount+0x15/0x20 mount_fs+0x5e/0x290 vfs_kern_mount+0x88/0x460 do_mount+0x398/0x31e0 ksys_mount+0xc6/0x150 __x64_sys_mount+0xea/0x190 do_syscall_64+0x122/0x590 entry_SYSCALL_64_after_hwframe+0x44/0xa9 It can be reproduced by the following step: 1. samba configured with: server max protocol = SMB2_10 2. mount -o vers=default When parse the mount version parameter, the 'ops' and 'vals' was setted to smb30, if negotiate result is smb21, just update the 'ops' to smb21, but the 'vals' is still smb30. When add lease context, the iov_base is allocated with smb21 ops, but the iov_len is initiallited with the smb30. Because the iov_len is longer than iov_base, when send the message, copy array out of bounds. we need to keep the 'ops' and 'vals' consistent. Fixes: 9764c02fcbad ("SMB3: Add support for multidialect negotiate (SMB2.1 and later)") Fixes: d5c7076b772a ("smb3: add smb3.1.1 to default dialect list") Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-27CIFS: keep FileInfo handle live during oplock breakAurelien Aptel
commit b98749cac4a695f084a5ff076f4510b23e353ecd upstream. In the oplock break handler, writing pending changes from pages puts the FileInfo handle. If the refcount reaches zero it closes the handle and waits for any oplock break handler to return, thus causing a deadlock. To prevent this situation: * We add a wait flag to cifsFileInfo_put() to decide whether we should wait for running/pending oplock break handlers * We keep an additionnal reference of the SMB FileInfo handle so that for the rest of the handler putting the handle won't close it. - The ref is bumped everytime we queue the handler via the cifs_queue_oplock_break() helper. - The ref is decremented at the end of the handler This bug was triggered by xfstest 464. Also important fix to address the various reports of oops in smb2_push_mandatory_locks Signed-off-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-20cifs: return -ENODATA when deleting an xattr that does not existRonnie Sahlberg
[ Upstream commit 2109464184919f81efd593b4008291448c522815 ] BUGZILLA: https://bugzilla.kernel.org/show_bug.cgi?id=202007 When deleting an xattr/EA: SMB2/3 servers will return SUCCESS when clients delete non-existing EAs. This means that we need to first QUERY the server and check if the EA exists or not so that we can return -ENODATA correctly when this happens. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-20cifs: Fix slab-out-of-bounds when tracing SMB tconPaulo Alcantara (SUSE)
[ Upstream commit 68ddb496800acdb46172b4981dc3753ea9b39c25 ] This patch fixes the following KASAN report: [ 779.044746] BUG: KASAN: slab-out-of-bounds in string+0xab/0x180 [ 779.044750] Read of size 1 at addr ffff88814f327968 by task trace-cmd/2812 [ 779.044756] CPU: 1 PID: 2812 Comm: trace-cmd Not tainted 5.1.0-rc1+ #62 [ 779.044760] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-0-ga698c89-prebuilt.qemu.org 04/01/2014 [ 779.044761] Call Trace: [ 779.044769] dump_stack+0x5b/0x90 [ 779.044775] ? string+0xab/0x180 [ 779.044781] print_address_description+0x6c/0x23c [ 779.044787] ? string+0xab/0x180 [ 779.044792] ? string+0xab/0x180 [ 779.044797] kasan_report.cold.3+0x1a/0x32 [ 779.044803] ? string+0xab/0x180 [ 779.044809] string+0xab/0x180 [ 779.044816] ? widen_string+0x160/0x160 [ 779.044822] ? vsnprintf+0x5bf/0x7f0 [ 779.044829] vsnprintf+0x4e7/0x7f0 [ 779.044836] ? pointer+0x4a0/0x4a0 [ 779.044841] ? seq_buf_vprintf+0x79/0xc0 [ 779.044848] seq_buf_vprintf+0x62/0xc0 [ 779.044855] trace_seq_printf+0x113/0x210 [ 779.044861] ? trace_seq_puts+0x110/0x110 [ 779.044867] ? trace_raw_output_prep+0xd8/0x110 [ 779.044876] trace_raw_output_smb3_tcon_class+0x9f/0xc0 [ 779.044882] print_trace_line+0x377/0x890 [ 779.044888] ? tracing_buffers_read+0x300/0x300 [ 779.044893] ? ring_buffer_read+0x58/0x70 [ 779.044899] s_show+0x6e/0x140 [ 779.044906] seq_read+0x505/0x6a0 [ 779.044913] vfs_read+0xaf/0x1b0 [ 779.044919] ksys_read+0xa1/0x130 [ 779.044925] ? kernel_write+0xa0/0xa0 [ 779.044931] ? __do_page_fault+0x3d5/0x620 [ 779.044938] do_syscall_64+0x63/0x150 [ 779.044944] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 779.044949] RIP: 0033:0x7f62c2c2db31 [ 779.044955] Code: fe ff ff 48 8d 3d 17 9e 09 00 48 83 ec 08 e8 96 02 02 00 66 0f 1f 44 00 00 8b 05 fa fc 2c 00 48 63 ff 85 c0 75 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 f3 c3 0f 1f 44 00 00 55 53 48 89 d5 48 89 [ 779.044958] RSP: 002b:00007ffd6e116678 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 779.044964] RAX: ffffffffffffffda RBX: 0000560a38be9260 RCX: 00007f62c2c2db31 [ 779.044966] RDX: 0000000000002000 RSI: 00007ffd6e116710 RDI: 0000000000000003 [ 779.044966] RDX: 0000000000002000 RSI: 00007ffd6e116710 RDI: 0000000000000003 [ 779.044969] RBP: 00007f62c2ef5420 R08: 0000000000000000 R09: 0000000000000003 [ 779.044972] R10: ffffffffffffffa8 R11: 0000000000000246 R12: 00007ffd6e116710 [ 779.044975] R13: 0000000000002000 R14: 0000000000000d68 R15: 0000000000002000 [ 779.044981] Allocated by task 1257: [ 779.044987] __kasan_kmalloc.constprop.5+0xc1/0xd0 [ 779.044992] kmem_cache_alloc+0xad/0x1a0 [ 779.044997] getname_flags+0x6c/0x2a0 [ 779.045003] user_path_at_empty+0x1d/0x40 [ 779.045008] do_faccessat+0x12a/0x330 [ 779.045012] do_syscall_64+0x63/0x150 [ 779.045017] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 779.045019] Freed by task 1257: [ 779.045023] __kasan_slab_free+0x12e/0x180 [ 779.045029] kmem_cache_free+0x85/0x1b0 [ 779.045034] filename_lookup.part.70+0x176/0x250 [ 779.045039] do_faccessat+0x12a/0x330 [ 779.045043] do_syscall_64+0x63/0x150 [ 779.045048] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 779.045052] The buggy address belongs to the object at ffff88814f326600 which belongs to the cache names_cache of size 4096 [ 779.045057] The buggy address is located 872 bytes to the right of 4096-byte region [ffff88814f326600, ffff88814f327600) [ 779.045058] The buggy address belongs to the page: [ 779.045062] page:ffffea00053cc800 count:1 mapcount:0 mapping:ffff88815b191b40 index:0x0 compound_mapcount: 0 [ 779.045067] flags: 0x200000000010200(slab|head) [ 779.045075] raw: 0200000000010200 dead000000000100 dead000000000200 ffff88815b191b40 [ 779.045081] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 [ 779.045083] page dumped because: kasan: bad access detected [ 779.045085] Memory state around the buggy address: [ 779.045089] ffff88814f327800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 779.045093] ffff88814f327880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 779.045097] >ffff88814f327900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 779.045099] ^ [ 779.045103] ffff88814f327980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 779.045107] ffff88814f327a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 779.045109] ================================================================== [ 779.045110] Disabling lock debugging due to kernel taint Correctly assign tree name str for smb3_tcon event. Signed-off-by: Paulo Alcantara (SUSE) <paulo@paulo.ac> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-20fix incorrect error code mapping for OBJECTID_NOT_FOUNDSteve French
[ Upstream commit 85f9987b236cf46e06ffdb5c225cf1f3c0acb789 ] It was mapped to EIO which can be confusing when user space queries for an object GUID for an object for which the server file system doesn't support (or hasn't saved one). As Amir Goldstein suggested this is similar to ENOATTR (equivalently ENODATA in Linux errno definitions) so changing NT STATUS code mapping for OBJECTID_NOT_FOUND to ENODATA. Signed-off-by: Steve French <stfrench@microsoft.com> CC: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-20cifs: fix that return -EINVAL when do dedupe operationXiaoli Feng
[ Upstream commit b073a08016a10f01dfb0d0b6c7fa89da0d544963 ] dedupe_file_range operations is combiled into remap_file_range. But it's always skipped for dedupe operations in function cifs_remap_file_range. Example to test: Before this patch: # dd if=/dev/zero of=cifs/file bs=1M count=1 # xfs_io -c "dedupe cifs/file 4k 64k 4k" cifs/file XFS_IOC_FILE_EXTENT_SAME: Invalid argument After this patch: # dd if=/dev/zero of=cifs/file bs=1M count=1 # xfs_io -c "dedupe cifs/file 4k 64k 4k" cifs/file XFS_IOC_FILE_EXTENT_SAME: Operation not supported Influence for xfstests: generic/091 generic/112 generic/127 generic/263 These tests report this error "do_copy_range:: Invalid argument" instead of "FIDEDUPERANGE: Invalid argument". Because there are still two bugs cause these test failed. https://bugzilla.kernel.org/show_bug.cgi?id=202935 https://bugzilla.kernel.org/show_bug.cgi?id=202785 Signed-off-by: Xiaoli Feng <fengxiaoli0714@gmail.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-17SMB3: Allow persistent handle timeout to be configurable on mountSteve French
commit ca567eb2b3f014d5be0f44c6f68b01a522f15ca4 upstream. Reconnecting after server or network failure can be improved (to maintain availability and protect data integrity) by allowing the client to choose the default persistent (or resilient) handle timeout in some use cases. Today we default to 0 which lets the server pick the default timeout (usually 120 seconds) but this can be problematic for some workloads. Add the new mount parameter to cifs.ko for SMB3 mounts "handletimeout" which enables the user to override the default handle timeout for persistent (mount option "persistenthandles") or resilient handles (mount option "resilienthandles"). Maximum allowed is 16 minutes (960000 ms). Units for the timeout are expressed in milliseconds. See section 2.2.14.2.12 and 2.2.31.3 of the MS-SMB2 protocol specification for more information. Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-05cifs: Fix NULL pointer dereference of devnameYao Liu
[ Upstream commit 68e2672f8fbd1e04982b8d2798dd318bf2515dd2 ] There is a NULL pointer dereference of devname in strspn() The oops looks something like: CIFS: Attempting to mount (null) BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 ... RIP: 0010:strspn+0x0/0x50 ... Call Trace: ? cifs_parse_mount_options+0x222/0x1710 [cifs] ? cifs_get_volume_info+0x2f/0x80 [cifs] cifs_setup_volume_info+0x20/0x190 [cifs] cifs_get_volume_info+0x50/0x80 [cifs] cifs_smb3_do_mount+0x59/0x630 [cifs] ? ida_alloc_range+0x34b/0x3d0 cifs_do_mount+0x11/0x20 [cifs] mount_fs+0x52/0x170 vfs_kern_mount+0x6b/0x170 do_mount+0x216/0xdc0 ksys_mount+0x83/0xd0 __x64_sys_mount+0x25/0x30 do_syscall_64+0x65/0x220 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix this by adding a NULL check on devname in cifs_parse_devname() Signed-off-by: Yao Liu <yotta.liu@ucloud.cn> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-05cifs: Accept validate negotiate if server return NT_STATUS_NOT_SUPPORTEDNamjae Jeon
[ Upstream commit 969ae8e8d4ee54c99134d3895f2adf96047f5bee ] Old windows version or Netapp SMB server will return NT_STATUS_NOT_SUPPORTED since they do not allow or implement FSCTL_VALIDATE_NEGOTIATE_INFO. The client should accept the response provided it's properly signed. See https://blogs.msdn.microsoft.com/openspecification/2012/06/28/smb3-secure-dialect-negotiation/ and MS-SMB2 validate negotiate response processing: https://msdn.microsoft.com/en-us/library/hh880630.aspx Samba client had already handled it. https://bugzilla.samba.org/attachment.cgi?id=13285&action=edit Signed-off-by: Namjae Jeon <linkinjeon@gmail.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-05cifs: use correct format charactersLouis Taylor
[ Upstream commit 259594bea574e515a148171b5cd84ce5cbdc028a ] When compiling with -Wformat, clang emits the following warnings: fs/cifs/smb1ops.c:312:20: warning: format specifies type 'unsigned short' but the argument has type 'unsigned int' [-Wformat] tgt_total_cnt, total_in_tgt); ^~~~~~~~~~~~ fs/cifs/cifs_dfs_ref.c:289:4: warning: format specifies type 'short' but the argument has type 'int' [-Wformat] ref->flags, ref->server_type); ^~~~~~~~~~ fs/cifs/cifs_dfs_ref.c:289:16: warning: format specifies type 'short' but the argument has type 'int' [-Wformat] ref->flags, ref->server_type); ^~~~~~~~~~~~~~~~ fs/cifs/cifs_dfs_ref.c:291:4: warning: format specifies type 'short' but the argument has type 'int' [-Wformat] ref->ref_flag, ref->path_consumed); ^~~~~~~~~~~~~ fs/cifs/cifs_dfs_ref.c:291:19: warning: format specifies type 'short' but the argument has type 'int' [-Wformat] ref->ref_flag, ref->path_consumed); ^~~~~~~~~~~~~~~~~~ The types of these arguments are unconditionally defined, so this patch updates the format character to the correct ones for ints and unsigned ints. Link: https://github.com/ClangBuiltLinux/linux/issues/378 Signed-off-by: Louis Taylor <louis@kragniz.eu> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-05CIFS: fix POSIX lock leak and invalid ptr derefAurelien Aptel
[ Upstream commit bc31d0cdcfbadb6258b45db97e93b1c83822ba33 ] We have a customer reporting crashes in lock_get_status() with many "Leaked POSIX lock" messages preceeding the crash. Leaked POSIX lock on dev=0x0:0x56 ... Leaked POSIX lock on dev=0x0:0x56 ... Leaked POSIX lock on dev=0x0:0x56 ... Leaked POSIX lock on dev=0x0:0x53 ... Leaked POSIX lock on dev=0x0:0x53 ... Leaked POSIX lock on dev=0x0:0x53 ... Leaked POSIX lock on dev=0x0:0x53 ... POSIX: fl_owner=ffff8900e7b79380 fl_flags=0x1 fl_type=0x1 fl_pid=20709 Leaked POSIX lock on dev=0x0:0x4b ino... Leaked locks on dev=0x0:0x4b ino=0xf911400000029: POSIX: fl_owner=ffff89f41c870e00 fl_flags=0x1 fl_type=0x1 fl_pid=19592 stack segment: 0000 [#1] SMP Modules linked in: binfmt_misc msr tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag rpcsec_gss_krb5 arc4 ecb auth_rpcgss nfsv4 md4 nfs nls_utf8 lockd grace cifs sunrpc ccm dns_resolver fscache af_packet iscsi_ibft iscsi_boot_sysfs vmw_vsock_vmci_transport vsock xfs libcrc32c sb_edac edac_core crct10dif_pclmul crc32_pclmul ghash_clmulni_intel drbg ansi_cprng vmw_balloon aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd joydev pcspkr vmxnet3 i2c_piix4 vmw_vmci shpchp fjes processor button ac btrfs xor raid6_pq sr_mod cdrom ata_generic sd_mod ata_piix vmwgfx crc32c_intel drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm serio_raw ahci libahci drm libata vmw_pvscsi sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_mod autofs4 Supported: Yes CPU: 6 PID: 28250 Comm: lsof Not tainted 4.4.156-94.64-default #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016 task: ffff88a345f28740 ti: ffff88c74005c000 task.ti: ffff88c74005c000 RIP: 0010:[<ffffffff8125dcab>] [<ffffffff8125dcab>] lock_get_status+0x9b/0x3b0 RSP: 0018:ffff88c74005fd90 EFLAGS: 00010202 RAX: ffff89bde83e20ae RBX: ffff89e870003d18 RCX: 0000000049534f50 RDX: ffffffff81a3541f RSI: ffffffff81a3544e RDI: ffff89bde83e20ae RBP: 0026252423222120 R08: 0000000020584953 R09: 000000000000ffff R10: 0000000000000000 R11: ffff88c74005fc70 R12: ffff89e5ca7b1340 R13: 00000000000050e5 R14: ffff89e870003d30 R15: ffff89e5ca7b1340 FS: 00007fafd64be800(0000) GS:ffff89f41fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001c80018 CR3: 000000a522048000 CR4: 0000000000360670 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000208 ffffffff81a3d6b6 ffff89e870003d30 ffff89e870003d18 ffff89e5ca7b1340 ffff89f41738d7c0 ffff89e870003d30 ffff89e5ca7b1340 ffffffff8125e08f 0000000000000000 ffff89bc22b67d00 ffff88c74005ff28 Call Trace: [<ffffffff8125e08f>] locks_show+0x2f/0x70 [<ffffffff81230ad1>] seq_read+0x251/0x3a0 [<ffffffff81275bbc>] proc_reg_read+0x3c/0x70 [<ffffffff8120e456>] __vfs_read+0x26/0x140 [<ffffffff8120e9da>] vfs_read+0x7a/0x120 [<ffffffff8120faf2>] SyS_read+0x42/0xa0 [<ffffffff8161cbc3>] entry_SYSCALL_64_fastpath+0x1e/0xb7 When Linux closes a FD (close(), close-on-exec, dup2(), ...) it calls filp_close() which also removes all posix locks. The lock struct is initialized like so in filp_close() and passed down to cifs ... lock.fl_type = F_UNLCK; lock.fl_flags = FL_POSIX | FL_CLOSE; lock.fl_start = 0; lock.fl_end = OFFSET_MAX; ... Note the FL_CLOSE flag, which hints the VFS code that this unlocking is done for closing the fd. filp_close() locks_remove_posix(filp, id); vfs_lock_file(filp, F_SETLK, &lock, NULL); return filp->f_op->lock(filp, cmd, fl) => cifs_lock() rc = cifs_setlk(file, flock, type, wait_flag, posix_lck, lock, unlock, xid); rc = server->ops->mand_unlock_range(cfile, flock, xid); if (flock->fl_flags & FL_POSIX && !rc) rc = locks_lock_file_wait(file, flock) Notice how we don't call locks_lock_file_wait() which does the generic VFS lock/unlock/wait work on the inode if rc != 0. If we are closing the handle, the SMB server is supposed to remove any locks associated with it. Similarly, cifs.ko frees and wakes up any lock and lock waiter when closing the file: cifs_close() cifsFileInfo_put(file->private_data) /* * Delete any outstanding lock records. We'll lose them when the file * is closed anyway. */ down_write(&cifsi->lock_sem); list_for_each_entry_safe(li, tmp, &cifs_file->llist->locks, llist) { list_del(&li->llist); cifs_del_lock_waiters(li); kfree(li); } list_del(&cifs_file->llist->llist); kfree(cifs_file->llist); up_write(&cifsi->lock_sem); So we can safely ignore unlocking failures in cifs_lock() if they happen with the FL_CLOSE flag hint set as both the server and the client take care of it during the actual closing. This is not a proper fix for the unlocking failure but it's safe and it seems to prevent the lock leakages and crashes the customer experiences. Signed-off-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: NeilBrown <neil@brown.name> Signed-off-by: Steve French <stfrench@microsoft.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-03-27SMB3: Fix SMB3.1.1 guest mounts to SambaSteve French
commit 8c11a607d1d9cd6e7f01fd6b03923597fb0ef95a upstream. Workaround problem with Samba responses to SMB3.1.1 null user (guest) mounts. The server doesn't set the expected flag in the session setup response so we have to do a similar check to what is done in smb3_validate_negotiate where we also check if the user is a null user (but not sec=krb5 since username might not be passed in on mount for Kerberos case). Note that the commit below tightened the conditions and forced signing for the SMB2-TreeConnect commands as per MS-SMB2. However, this should only apply to normal user sessions and not for cases where there is no user (even if server forgets to set the flag in the response) since we don't have anything useful to sign with. This is especially important now that the more secure SMB3.1.1 protocol is in the default dialect list. An earlier patch ("cifs: allow guest mounts to work for smb3.11") fixed the guest mounts to Windows. Fixes: 6188f28bf608 ("Tree connect for SMB3.1.1 must be signed for non-encrypted shares") Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Paulo Alcantara <palcantara@suse.de> CC: Stable <stable@vger.kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-27cifs: allow guest mounts to work for smb3.11Ronnie Sahlberg
commit e71ab2aa06f731a944993120b0eef1556c63b81c upstream. Fix Guest/Anonymous sessions so that they work with SMB 3.11. The commit noted below tightened the conditions and forced signing for the SMB2-TreeConnect commands as per MS-SMB2. However, this should only apply to normal user sessions and not for Guest/Anonumous sessions. Fixes: 6188f28bf608 ("Tree connect for SMB3.1.1 must be signed for non-encrypted shares") Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-23smb3: make default i/o size for smb3 mounts largerSteve French
commit e8506d25f740fd058791cc12a6dfa9386ada6b96 upstream. We negotiate rsize mounts (and it can be overridden by user) to typically 4MB, so using larger default I/O sizes from userspace (changing to 1MB default i/o size returned by stat) the performance is much better (and not just for long latency network connections) in most use cases for SMB3 than the default I/O size (which ends up being 128K for cp and can be even smaller for cp). This can be 4x slower or worse depending on network latency. By changing inode->blocksize from 32K (which was perhaps ok for very old SMB1/CIFS) to a larger value, 1MB (but still less than max size negotiated with the server which is 4MB, in order to minimize risk) it significantly increases performance for the noncached case, and slightly increases it for the cached case. This can be changed by the user on mount (specifying bsize= values from 16K to 16MB) to tune better for performance for applications that depend on blocksize. Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-23CIFS: Fix read after write for files with read cachingPavel Shilovsky
commit 6dfbd84684700cb58b34e8602c01c12f3d2595c8 upstream. When we have a READ lease for a file and have just issued a write operation to the server we need to purge the cache and set oplock/lease level to NONE to avoid reading stale data. Currently we do that only if a write operation succedeed thus not covering cases when a request was sent to the server but a negative error code was returned later for some other reasons (e.g. -EIOCBQUEUED or -EINTR). Fix this by turning off caching regardless of the error code being returned. The patches fixes generic tests 075 and 112 from the xfs-tests. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-23CIFS: Do not skip SMB2 message IDs on send failuresPavel Shilovsky
commit c781af7e0c1fed9f1d0e0ec31b86f5b21a8dca17 upstream. When we hit failures during constructing MIDs or sending PDUs through the network, we end up not using message IDs assigned to the packet. The next SMB packet will skip those message IDs and continue with the next one. This behavior may lead to a server not granting us credits until we use the skipped IDs. Fix this by reverting the current ID to the original value if any errors occur before we push the packet through the network stack. This patch fixes the generic/310 test from the xfs-tests. Cc: <stable@vger.kernel.org> # 4.19.x Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-23CIFS: Do not reset lease state to NONE on lease breakPavel Shilovsky
commit 7b9b9edb49ad377b1e06abf14354c227e9ac4b06 upstream. Currently on lease break the client sets a caching level twice: when oplock is detected and when oplock is processed. While the 1st attempt sets the level to the value provided by the server, the 2nd one resets the level to None unconditionally. This happens because the oplock/lease processing code was changed to avoid races between page cache flushes and oplock breaks. The commit c11f1df5003d534 ("cifs: Wait for writebacks to complete before attempting write.") fixed the races for oplocks but didn't apply the same changes for leases resulting in overwriting the server granted value to None. Fix this by properly processing lease breaks. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-23CIFS: Fix leaking locked VFS cache pages in writeback retryPavel Shilovsky
commit 165df9a080b6863ae286fa01780c13d87cd81076 upstream. If we don't find a writable file handle when retrying writepages we break of the loop and do not unlock and put pages neither from wdata2 nor from the original wdata. Fix this by walking through all the remaining pages and cleanup them properly. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-31cifs: update internal module version numberSteve French
To 2.17 Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-31CIFS: fix use-after-free of the lease keysAurelien Aptel
The request buffers are freed right before copying the pointers. Use the func args instead which are identical and still valid. Simple reproducer (requires KASAN enabled) on a cifs mount: echo foo > foo ; tail -f foo & rm foo Cc: <stable@vger.kernel.org> # 4.20 Fixes: 179e44d49c2f ("smb3: add tracepoint for sending lease break responses to server") Signed-off-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Paulo Alcantara <palcantara@suse.de>
2019-01-29CIFS: Do not consider -ENODATA as stat failure for readsPavel Shilovsky
When doing reads beyound the end of a file the server returns error STATUS_END_OF_FILE error which is mapped to -ENODATA. Currently we report it as a failure which confuses read stats. Change it to not consider -ENODATA as failure for stat purposes. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org>
2019-01-29CIFS: Do not count -ENODATA as failure for query directoryPavel Shilovsky
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org>
2019-01-29CIFS: Fix trace command logging for SMB2 reads and writesPavel Shilovsky
Currently we log success once we send an async IO request to the server. Instead we need to analyse a response and then log success or failure for a particular command. Also fix argument list for read logging. Cc: <stable@vger.kernel.org> # 4.18 Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-29CIFS: Fix possible oops and memory leaks in async IOPavel Shilovsky
Allocation of a page array for non-cached IO was separated from allocation of rdata and wdata structures and this introduced memory leaks and a possible null pointer dereference. This patch fixes these problems. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-29cifs: limit amount of data we request for xattrs to CIFSMaxBufSizeRonnie Sahlberg
minus the various headers and blobs that will be part of the reply. or else we might trigger a session reconnect. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2019-01-29cifs: fix computation for MAX_SMB2_HDR_SIZERonnie Sahlberg
The size of the fixed part of the create response is 88 bytes not 56. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2019-01-24cifs: print CIFSMaxBufSize as part of /proc/fs/cifs/DebugDataRonnie Sahlberg
Was helpful in debug for some recent problems. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24smb3: add credits we receive from oplock/break PDUsRonnie Sahlberg
Otherwise we gradually leak credits leading to potential hung session. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> CC: Stable <stable@vger.kernel.org> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Fix mounts if the client is low on creditsPavel Shilovsky
If the server doesn't grant us at least 3 credits during the mount we won't be able to complete it because query path info operation requires 3 credits. Use the cached file handle if possible to allow the mount to succeed. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Do not assume one credit for async responsesPavel Shilovsky
If we don't receive a response we can't assume that the server granted one credit. Assume zero credits in such cases. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Fix credit calculations in compound mid callbackPavel Shilovsky
The current code doesn't do proper accounting for credits in SMB1 case: it adds one credit per response only if we get a complete response while it needs to return it unconditionally. Fix this and also include malformed responses for SMB2+ into accounting for credits because such responses have Credit Granted field, thus nothing prevents to get a proper credit value from them. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Fix credit calculation for encrypted reads with errorsPavel Shilovsky
We do need to account for credits received in error responses to read requests on encrypted sessions. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Fix credits calculations for reads with errorsPavel Shilovsky
Currently we mark MID as malformed if we get an error from server in a read response. This leads to not properly processing credits in the readv callback. Fix this by marking such a response as normal received response and process it appropriately. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Do not reconnect TCP session in add_credits()Pavel Shilovsky
When executing add_credits() we currently call cifs_reconnect() if the number of credits is zero and there are no requests in flight. In this case we may call cifs_reconnect() recursively twice and cause memory corruption given the following sequence of functions: mid1.callback() -> add_credits() -> cifs_reconnect() -> -> mid2.callback() -> add_credits() -> cifs_reconnect(). Fix this by avoiding to call cifs_reconnect() in add_credits() and checking for zero credits in the demultiplex thread. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24smb3: Cleanup license messThomas Gleixner
Precise and non-ambiguous license information is important. The recently added aegis header file has a SPDX license identifier, which is nice, but at the same time it has a contradictionary license boiler plate text. SPDX-License-Identifier: GPL-2.0 versus * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. Oh well. Assuming that the SPDX identifier is correct and according to x86/hyper-v contributions from Microsoft GPL V2 only is the usual license. Remove the boiler plate as it is wrong and even if correct it is redundant. Fixes: eccb4422cf97 ("smb3: Add ftrace tracepoints for improved SMB3 debugging") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Steve French <sfrench@samba.org> Cc: linux-cifs@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24CIFS: Fix possible hang during async MTU reads and writesPavel Shilovsky
When doing MTU i/o we need to leave some credits for possible reopen requests and other operations happening in parallel. Currently we leave 1 credit which is not enough even for reopen only: we need at least 2 credits if durable handle reconnect fails. Also there may be other operations at the same time including compounding ones which require 3 credits at a time each. Fix this by leaving 8 credits which is big enough to cover most scenarios. Was able to reproduce this when server was configured to give out fewer credits than usual. The proper fix would be to reconnect a file handle first and then obtain credits for an MTU request but this leads to bigger code changes and should happen in other patches. Cc: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-24cifs: fix memory leak of an allocated cifs_ntsd structureColin Ian King
The call to SMB2_queary_acl can allocate memory to pntsd and also return a failure via a call to SMB2_query_acl (and then query_info). This occurs when query_info allocates the structure and then in query_info the call to smb2_validate_and_copy_iov fails. Currently the failure just returns without kfree'ing pntsd hence causing a memory leak. Currently, *data is allocated if it's not already pointing to a buffer, so it needs to be kfree'd only if was allocated in query_info, so the fix adds an allocated flag to track this. Also set *dlen to zero on an error just to be safe since *data is kfree'd. Also set errno to -ENOMEM if the allocation of *data fails. Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Dan Carpener <dan.carpenter@oracle.com>
2019-01-11cifs: update internal module version numberSteve French
To 2.16 Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-11CIFS: Fix error paths in writeback codePavel Shilovsky
This patch aims to address writeback code problems related to error paths. In particular it respects EINTR and related error codes and stores and returns the first error occurred during writeback. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Acked-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-11CIFS: Move credit processing to mid callbacks for SMB3Pavel Shilovsky
Currently we account for credits in the thread initiating a request and waiting for a response. The demultiplex thread receives the response, wakes up the thread and the latter collects credits from the response buffer and add them to the server structure on the client. This approach is not accurate, because it may race with reconnect events in the demultiplex thread which resets the number of credits. Fix this by moving credit processing to new mid callbacks that collect credits granted by the server from the response in the demultiplex thread. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-11CIFS: Fix credits calculation for cancelled requestsPavel Shilovsky
If a request is cancelled, we can't assume that the server returns 1 credit back. Instead we need to wait for a response and process the number of credits granted by the server. Create a separate mid callback for cancelled request, parse the number of credits in a response buffer and add them to the client's credits. If the didn't get a response (no response buffer available) assume 0 credits granted. The latter most probably happens together with session reconnect, so the client's credits are adjusted anyway. Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2019-01-11cifs: Fix potential OOB access of lock element arrayRoss Lagerwall
If maxBuf is small but non-zero, it could result in a zero sized lock element array which we would then try and access OOB. Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org>
2019-01-11cifs: Limit memory used by lock request calls to a pageRoss Lagerwall
The code tries to allocate a contiguous buffer with a size supplied by the server (maxBuf). This could fail if memory is fragmented since it results in high order allocations for commonly used server implementations. It is also wasteful since there are probably few locks in the usual case. Limit the buffer to be no larger than a page to avoid memory allocation failures due to fragmentation. Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Signed-off-by: Steve French <stfrench@microsoft.com>