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Subject[PATCH 5.15 07/28] xfs: Fix the free logic of state in xfs_attr_node_hasname
Date
From: Yang Xu <xuyang2018.jy@fujitsu.com>

[ Upstream commit a1de97fe296c52eafc6590a3506f4bbd44ecb19a ]

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 07120f1abdff ("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: 07120f1abdff ("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>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/xfs/libxfs/xfs_attr.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -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);

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