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[PATCH] xfs: fix off-by-one error in xfs_attr3_rmt_verify

To: "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
Subject: [PATCH] xfs: fix off-by-one error in xfs_attr3_rmt_verify
From: Jeff Liu <jeff.liu@xxxxxxxxxx>
Date: Wed, 01 Jan 2014 19:28:03 +0800
Delivered-to: xfs@xxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0
From: Jie Liu <jeff.liu@xxxxxxxxxx>

With CRC check is enabled, if trying to set an attributes value just
equal to the maximum size of XATTR_SIZE_MAX would cause the v3 remote
attr write verification procedure failure, which would yield the back
trace like below:

<snip>
XFS (sda7): Internal error xfs_attr3_rmt_write_verify at line 191 of file 
fs/xfs/xfs_attr_remote.c
<snip>
Call Trace:
[<ffffffff816f0042>] dump_stack+0x45/0x56
[<ffffffffa0d99c8b>] xfs_error_report+0x3b/0x40 [xfs]
[<ffffffffa0d96edd>] ? _xfs_buf_ioapply+0x6d/0x390 [xfs]
[<ffffffffa0d99ce5>] xfs_corruption_error+0x55/0x80 [xfs]
[<ffffffffa0dbef6b>] xfs_attr3_rmt_write_verify+0x14b/0x1a0 [xfs]
[<ffffffffa0d96edd>] ? _xfs_buf_ioapply+0x6d/0x390 [xfs]
[<ffffffffa0d97315>] ? xfs_bdstrat_cb+0x55/0xb0 [xfs]
[<ffffffffa0d96edd>] _xfs_buf_ioapply+0x6d/0x390 [xfs]
[<ffffffff81184cda>] ? vm_map_ram+0x31a/0x460
[<ffffffff81097230>] ? wake_up_state+0x20/0x20
[<ffffffffa0d97315>] ? xfs_bdstrat_cb+0x55/0xb0 [xfs]
[<ffffffffa0d9726b>] xfs_buf_iorequest+0x6b/0xc0 [xfs]
[<ffffffffa0d97315>] xfs_bdstrat_cb+0x55/0xb0 [xfs]
[<ffffffffa0d97906>] xfs_bwrite+0x46/0x80 [xfs]
[<ffffffffa0dbfa94>] xfs_attr_rmtval_set+0x334/0x490 [xfs]
[<ffffffffa0db84aa>] xfs_attr_leaf_addname+0x24a/0x410 [xfs]
[<ffffffffa0db8893>] xfs_attr_set_int+0x223/0x470 [xfs]
[<ffffffffa0db8b76>] xfs_attr_set+0x96/0xb0 [xfs]
[<ffffffffa0db13b2>] xfs_xattr_set+0x42/0x70 [xfs]
[<ffffffff811df9b2>] generic_setxattr+0x62/0x80
[<ffffffff811e0213>] __vfs_setxattr_noperm+0x63/0x1b0
[<ffffffff81307afe>] ? evm_inode_setxattr+0xe/0x10
[<ffffffff811e0415>] vfs_setxattr+0xb5/0xc0
[<ffffffff811e054e>] setxattr+0x12e/0x1c0
[<ffffffff811c6e82>] ? final_putname+0x22/0x50
[<ffffffff811c708b>] ? putname+0x2b/0x40
[<ffffffff811cc4bf>] ? user_path_at_empty+0x5f/0x90
[<ffffffff811bdfd9>] ? __sb_start_write+0x49/0xe0
[<ffffffff81168589>] ? vm_mmap_pgoff+0x99/0xc0
[<ffffffff811e07df>] SyS_setxattr+0x8f/0xe0
[<ffffffff81700c2d>] system_call_fastpath+0x1a/0x1f

Tests:
    setfattr -n user.longxattr -v `perl -e 'print "A"x65536'` testfile

This patch fix it to check the remote EA size is greater than the
XATTR_SIZE_MAX rather than more than or equal to it, because it's
valid if the specified EA value size is equal to the limitation as
per VFS setxattr interface.

Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
---
 fs/xfs/xfs_attr_remote.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_attr_remote.c b/fs/xfs/xfs_attr_remote.c
index 739e0a5..5549d69 100644
--- a/fs/xfs/xfs_attr_remote.c
+++ b/fs/xfs/xfs_attr_remote.c
@@ -110,7 +110,7 @@ xfs_attr3_rmt_verify(
        if (be32_to_cpu(rmt->rm_bytes) > fsbsize - sizeof(*rmt))
                return false;
        if (be32_to_cpu(rmt->rm_offset) +
-                               be32_to_cpu(rmt->rm_bytes) >= XATTR_SIZE_MAX)
+                               be32_to_cpu(rmt->rm_bytes) > XATTR_SIZE_MAX)
                return false;
        if (rmt->rm_owner == 0)
                return false;
-- 
1.8.3.2

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