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ocfs2: bound-check dir entries in the inline-data re-validation scan

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ocfs2_dir_foreach_blk_id() re-scans the inline data area the same way
ocfs2_dir_foreach_blk_el() re-scans a directory block, and is missing the
same two bounds:

	for (i = 0; i < i_size_read(inode) && i < offset; ) {
		de = (struct ocfs2_dir_entry *)(data->id_data + i);
		if (le16_to_cpu(de->rec_len) < OCFS2_DIR_REC_LEN(1))
			break;
		i += le16_to_cpu(de->rec_len);
	}

ocfs2_validate_inode_block() keeps i_size inside the inline area:

	if (le16_to_cpu(data->id_count) >
	    ocfs2_max_inline_data_with_xattr(sb, di))
	if (le64_to_cpu(di->i_size) > le16_to_cpu(data->id_count))

and that area runs to the end of the inode block, so for a full inline
directory data->id_data + i_size is the end of di_bh->b_data.  A bogus
rec_len leaves i in the last OCFS2_DIR_REC_LEN(1) - 1 bytes of it, and
de->rec_len, at byte offset 8 within the entry, is then read past the
block.

The emit loop below hands i_size_read(inode) to ocfs2_check_dir_entry(),
which refuses both an entry that close to the end and one whose rec_len
runs past it.  Apply the same two bounds to the re-validation scan,
reading i_size once into a local as ocfs2_check_dir_entry() takes it as
@size.

Unlike the extent case there is no mask to corrupt here: an unbounded i
only sets ctx->pos past i_size, which ends the readdir early rather than
moving it to the wrong place.

Link: https://lore.kernel.org/20260811024337.3972976-3-zhanxusheng@xiaomi.com
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.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: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Zhan Xusheng 2026-08-11 10:43:37 +08:00 • committed by Andrew Morton
commit 763c097f71
1 changed files with 10 additions and 4 deletions
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