ocfs2_validate_xattr_block() checks the xattr block header before the
block reaches higher-level xattr users, but it does not verify that a
non-indexed block's xh_count and entry offsets fit inside the block.
Indexed buckets likewise reach list/get consumers after ECC without an
entry-bounds check.
Use the flat xattr entry validator for non-indexed external xattr blocks,
and use a bucket-specific validator for indexed buckets at metadata read
time. The bucket validator keeps the entry array bounded by the first
bucket block while checking name/value offsets against the bucket block
they target.
Reject corrupted external xattr metadata before listxattr() or getxattr()
can walk out-of-range entry arrays or name/value offsets.
Validation reproduced this kernel report:
BUG: KASAN: use-after-free in ocfs2_xattr_list_entries+0xd7/0x190
Read of size 1 at addr ffff88810a654007 by task ocfs2_xattr_lis/630
Call Trace:
dump_stack_lvl+0x66/0xa0
print_report+0xce/0x630
kasan_report+0xe0/0x110
ocfs2_xattr_list_entries+0xd7/0x190
ocfs2_listxattr+0x3f6/0x610
listxattr+0x90/0xe0
path_listxattrat+0xed/0x220
do_syscall_64+0x115/0x6a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Link: https://lore.kernel.org/20260705025311.3429854-3-zzzccc427@gmail.com
Fixes: cf1d6c763f ("ocfs2: Add extended attribute support")
Fixes: 0c044f0b24 ("ocfs2: Add xattr bucket iteration for large numbers of EAs")
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Assisted-by: Codex:gpt-5.5
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: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2cf82b46d5