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xfs: Fix the free logic of state in xfs_attr_node_hasname

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When testing xfstests xfs/126 on lastest upstream kernel, it will hang on some machine.
Adding a getxattr operation after xattr corrupted, I can reproduce it 100%.

The deadlock as below:
[983.923403] task:setfattr        state:D stack:    0 pid:17639 ppid: 14687 flags:0x00000080
[  983.923405] Call Trace:
[  983.923410]  __schedule+0x2c4/0x700
[  983.923412]  schedule+0x37/0xa0
[  983.923414]  schedule_timeout+0x274/0x300
[  983.923416]  __down+0x9b/0xf0
[  983.923451]  ? xfs_buf_find.isra.29+0x3c8/0x5f0 [xfs]
[  983.923453]  down+0x3b/0x50
[  983.923471]  xfs_buf_lock+0x33/0xf0 [xfs]
[  983.923490]  xfs_buf_find.isra.29+0x3c8/0x5f0 [xfs]
[  983.923508]  xfs_buf_get_map+0x4c/0x320 [xfs]
[  983.923525]  xfs_buf_read_map+0x53/0x310 [xfs]
[  983.923541]  ? xfs_da_read_buf+0xcf/0x120 [xfs]
[  983.923560]  xfs_trans_read_buf_map+0x1cf/0x360 [xfs]
[  983.923575]  ? xfs_da_read_buf+0xcf/0x120 [xfs]
[  983.923590]  xfs_da_read_buf+0xcf/0x120 [xfs]
[  983.923606]  xfs_da3_node_read+0x1f/0x40 [xfs]
[  983.923621]  xfs_da3_node_lookup_int+0x69/0x4a0 [xfs]
[  983.923624]  ? kmem_cache_alloc+0x12e/0x270
[  983.923637]  xfs_attr_node_hasname+0x6e/0xa0 [xfs]
[  983.923651]  xfs_has_attr+0x6e/0xd0 [xfs]
[  983.923664]  xfs_attr_set+0x273/0x320 [xfs]
[  983.923683]  xfs_xattr_set+0x87/0xd0 [xfs]
[  983.923686]  __vfs_removexattr+0x4d/0x60
[  983.923688]  __vfs_removexattr_locked+0xac/0x130
[  983.923689]  vfs_removexattr+0x4e/0xf0
[  983.923690]  removexattr+0x4d/0x80
[  983.923693]  ? __check_object_size+0xa8/0x16b
[  983.923695]  ? strncpy_from_user+0x47/0x1a0
[  983.923696]  ? getname_flags+0x6a/0x1e0
[  983.923697]  ? _cond_resched+0x15/0x30
[  983.923699]  ? __sb_start_write+0x1e/0x70
[  983.923700]  ? mnt_want_write+0x28/0x50
[  983.923701]  path_removexattr+0x9b/0xb0
[  983.923702]  __x64_sys_removexattr+0x17/0x20
[  983.923704]  do_syscall_64+0x5b/0x1a0
[  983.923705]  entry_SYSCALL_64_after_hwframe+0x65/0xca
[  983.923707] RIP: 0033:0x7f080f10ee1b

When getxattr calls xfs_attr_node_get function, xfs_da3_node_lookup_int fails with EFSCORRUPTED in
xfs_attr_node_hasname because we have use blocktrash to random it in xfs/126. So it
free state in internal and xfs_attr_node_get doesn't do xfs_buf_trans release job.

Then subsequent removexattr will hang because of it.

This bug was introduced by kernel commit 07120f1abd ("xfs: Add xfs_has_attr and subroutines").
It adds xfs_attr_node_hasname helper and said caller will be responsible for freeing the state
in this case. But xfs_attr_node_hasname will free state itself instead of caller if
xfs_da3_node_lookup_int fails.

Fix this bug by moving the step of free state into caller.

Also, use "goto error/out" instead of returning error directly in xfs_attr_node_addname_find_attr and
xfs_attr_node_removename_setup function because we should free state ourselves.

Fixes: 07120f1abd ("xfs: Add xfs_has_attr and subroutines")
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Yang Xu 2021-11-24 10:06:02 -08:00 committed by Darrick J. Wong
parent 1360572566
commit a1de97fe29
1 changed files with 7 additions and 10 deletions
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17
fs/xfs/libxfs/xfs_attr.c
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@ -1077,21 +1077,18 @@ xfs_attr_node_hasname(
state = xfs_da_state_alloc(args);
if (statep != NULL)
*statep = NULL;
*statep = state;
/*
* Search to see if name exists, and get back a pointer to it.
*/
error = xfs_da3_node_lookup_int(state, &retval);
if (error) {
xfs_da_state_free(state);
return error;
}
if (error)
retval = error;
if (statep != NULL)
*statep = state;
else
if (!statep)
xfs_da_state_free(state);
return retval;
}
@ -1112,7 +1109,7 @@ xfs_attr_node_addname_find_attr(
*/
retval = xfs_attr_node_hasname(args, &dac->da_state);
if (retval != -ENOATTR && retval != -EEXIST)
return retval;
goto error;
if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
goto error;
@ -1337,7 +1334,7 @@ int xfs_attr_node_removename_setup(
error = xfs_attr_node_hasname(args, state);
if (error != -EEXIST)
return error;
goto out;
error = 0;
ASSERT((*state)->path.blk[(*state)->path.active - 1].bp != NULL);