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Andrew Kanner 0b63c0e01f ocfs2: remove entry once instead of null-ptr-dereference in ocfs2_xa_remove()
Syzkaller is able to provoke null-ptr-dereference in ocfs2_xa_remove():

[   57.319872] (a.out,1161,7):ocfs2_xa_remove:2028 ERROR: status = -12
[   57.320420] (a.out,1161,7):ocfs2_xa_cleanup_value_truncate:1999 ERROR: Partial truncate while removing xattr overlay.upper.  Leaking 1 clusters and removing the entry
[   57.321727] BUG: kernel NULL pointer dereference, address: 0000000000000004
[...]
[   57.325727] RIP: 0010:ocfs2_xa_block_wipe_namevalue+0x2a/0xc0
[...]
[   57.331328] Call Trace:
[   57.331477]  <TASK>
[...]
[   57.333511]  ? do_user_addr_fault+0x3e5/0x740
[   57.333778]  ? exc_page_fault+0x70/0x170
[   57.334016]  ? asm_exc_page_fault+0x2b/0x30
[   57.334263]  ? __pfx_ocfs2_xa_block_wipe_namevalue+0x10/0x10
[   57.334596]  ? ocfs2_xa_block_wipe_namevalue+0x2a/0xc0
[   57.334913]  ocfs2_xa_remove_entry+0x23/0xc0
[   57.335164]  ocfs2_xa_set+0x704/0xcf0
[   57.335381]  ? _raw_spin_unlock+0x1a/0x40
[   57.335620]  ? ocfs2_inode_cache_unlock+0x16/0x20
[   57.335915]  ? trace_preempt_on+0x1e/0x70
[   57.336153]  ? start_this_handle+0x16c/0x500
[   57.336410]  ? preempt_count_sub+0x50/0x80
[   57.336656]  ? _raw_read_unlock+0x20/0x40
[   57.336906]  ? start_this_handle+0x16c/0x500
[   57.337162]  ocfs2_xattr_block_set+0xa6/0x1e0
[   57.337424]  __ocfs2_xattr_set_handle+0x1fd/0x5d0
[   57.337706]  ? ocfs2_start_trans+0x13d/0x290
[   57.337971]  ocfs2_xattr_set+0xb13/0xfb0
[   57.338207]  ? dput+0x46/0x1c0
[   57.338393]  ocfs2_xattr_trusted_set+0x28/0x30
[   57.338665]  ? ocfs2_xattr_trusted_set+0x28/0x30
[   57.338948]  __vfs_removexattr+0x92/0xc0
[   57.339182]  __vfs_removexattr_locked+0xd5/0x190
[   57.339456]  ? preempt_count_sub+0x50/0x80
[   57.339705]  vfs_removexattr+0x5f/0x100
[...]

Reproducer uses faultinject facility to fail ocfs2_xa_remove() ->
ocfs2_xa_value_truncate() with -ENOMEM.

In this case the comment mentions that we can return 0 if
ocfs2_xa_cleanup_value_truncate() is going to wipe the entry
anyway. But the following 'rc' check is wrong and execution flow do
'ocfs2_xa_remove_entry(loc);' twice:
* 1st: in ocfs2_xa_cleanup_value_truncate();
* 2nd: returning back to ocfs2_xa_remove() instead of going to 'out'.

Fix this by skipping the 2nd removal of the same entry and making
syzkaller repro happy.

Link: https://lkml.kernel.org/r/20241103193845.2940988-1-andrew.kanner@gmail.com
Fixes: 399ff3a748 ("ocfs2: Handle errors while setting external xattr values.")
Signed-off-by: Andrew Kanner <andrew.kanner@gmail.com>
Reported-by: syzbot+386ce9e60fa1b18aac5b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/671e13ab.050a0220.2b8c0f.01d0.GAE@google.com/T/
Tested-by: syzbot+386ce9e60fa1b18aac5b@syzkaller.appspotmail.com
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-07 14:14:59 -08:00
arch mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling 2024-11-05 16:49:55 -08:00
block block-6.12-20241101 2024-11-01 13:41:55 -10:00
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Documentation mm: fix docs for the kernel parameter `thp_anon=` 2024-11-07 14:14:59 -08:00
drivers phy fixes for 6.12 2024-11-03 10:19:34 -10:00
fs ocfs2: remove entry once instead of null-ptr-dereference in ocfs2_xa_remove() 2024-11-07 14:14:59 -08:00
include signal: restore the override_rlimit logic 2024-11-07 14:14:59 -08:00
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COPYING
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MAINTAINERS Char/Misc/IIO driver fixes for 6.12-rc6 2024-11-03 08:45:03 -10:00
Makefile Linux 6.12-rc6 2024-11-03 14:05:52 -10:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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