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ocfs2: adjust ocfs2_xa_remove_entry() to match UBSAN boundary checks

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After introducing 2f26f58df0 ("ocfs2: annotate flexible array members
with __counted_by_le()"), syzbot has reported the following issue:

UBSAN: array-index-out-of-bounds in fs/ocfs2/xattr.c:1955:3
index 2 is out of range for type 'struct ocfs2_xattr_entry[]
__counted_by(xh_count)' (aka 'struct ocfs2_xattr_entry[]')
...
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:233
 __ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:455
 ocfs2_xa_remove_entry+0x36d/0x3e0 fs/ocfs2/xattr.c:1955
 ...

To address this issue, 'xh_entries[]' member removal should be performed
before actually changing 'xh_count', thus making sure that all array
accesses matches the boundary checks performed by UBSAN.

Link: https://lkml.kernel.org/r/20251211155949.774485-1-dmantipov@yandex.ru
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Reported-by: syzbot+cf96bc82a588a27346a8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=cf96bc82a588a27346a8
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Deepanshu Kartikey <kartikey406@gmail.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dmitry Antipov
2025-12-11 18:59:49 +03:00
committed by Andrew Morton
parent 1524af3685
commit d3cd8de2e1
1 changed files with 3 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
fs/ocfs2/xattr.c
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@@ -1971,8 +1971,7 @@ static void ocfs2_xa_remove_entry(struct ocfs2_xa_loc *loc)
ocfs2_xa_wipe_namevalue(loc);
loc->xl_entry = NULL;
le16_add_cpu(&xh->xh_count, -1);
count = le16_to_cpu(xh->xh_count);
count = le16_to_cpu(xh->xh_count) - 1;
/*
* Only zero out the entry if there are more remaining. This is
@@ -1987,6 +1986,8 @@ static void ocfs2_xa_remove_entry(struct ocfs2_xa_loc *loc)
memset(&xh->xh_entries[count], 0,
sizeof(struct ocfs2_xattr_entry));
}
xh->xh_count = cpu_to_le16(count);
}
/*