Commit 775c1738 authored by Joseph Qi's avatar Joseph Qi Committed by Andrew Morton
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ocfs2: validate dx_root extent list fields during block read 

Patch series "ocfs2: consolidate extent list validation into block read
callbacks".

ocfs2 validates extent list fields (l_count, l_next_free_rec) at various
points during extent tree traversal.  This is fragile because each caller
must remember to check for corrupted on-disk data before using it.

This series moves those checks into the block read validation callbacks
(ocfs2_validate_dx_root and ocfs2_validate_extent_block), so corrupted
fields are caught early at block read time.  Redundant post-read checks
are then removed.


This patch (of 4):

Move the extent list l_count validation from ocfs2_dx_dir_lookup_rec()
into ocfs2_validate_dx_root(), so that corrupted on-disk fields are caught
early at block read time rather than during directory lookups.

Additionally, add a l_next_free_rec <= l_count check to prevent
out-of-bounds access when iterating over extent records.

Both checks are skipped for inline dx roots (OCFS2_DX_FLAG_INLINE), which
use dr_entries instead of dr_list.

Link: https://lkml.kernel.org/r/20260403090803.3860971-1-joseph.qi@linux.alibaba.com
Link: https://lkml.kernel.org/r/20260403090803.3860971-2-joseph.qi@linux.alibaba.com


Signed-off-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: default avatarHeming Zhao <heming.zhao@suse.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>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7de554ca

fs/ocfs2/dir.c

+25 −9
Original line number Diff line number Diff line
@@ -593,7 +593,7 @@ static int ocfs2_validate_dx_root(struct super_block *sb, 
		mlog(ML_ERROR,

		     "Checksum failed for dir index root block %llu\n",

		     (unsigned long long)bh->b_blocknr);

		return ret;

		goto bail;

	}



	if (!OCFS2_IS_VALID_DX_ROOT(dx_root)) {
@@ -601,8 +601,32 @@ static int ocfs2_validate_dx_root(struct super_block *sb, 
				  "Dir Index Root # %llu has bad signature %.*s\n",

				  (unsigned long long)le64_to_cpu(dx_root->dr_blkno),

				  7, dx_root->dr_signature);

		goto bail;

	}



	if (!(dx_root->dr_flags & OCFS2_DX_FLAG_INLINE)) {

		struct ocfs2_extent_list *el = &dx_root->dr_list;



		if (le16_to_cpu(el->l_count) != ocfs2_extent_recs_per_dx_root(sb)) {

			ret = ocfs2_error(sb,

					  "Dir Index Root # %llu has invalid l_count %u (expected %u)\n",

					  (unsigned long long)le64_to_cpu(dx_root->dr_blkno),

					  le16_to_cpu(el->l_count),

					  ocfs2_extent_recs_per_dx_root(sb));

			goto bail;

		}



		if (le16_to_cpu(el->l_next_free_rec) > le16_to_cpu(el->l_count)) {

			ret = ocfs2_error(sb,

					  "Dir Index Root # %llu has invalid l_next_free_rec %u (l_count %u)\n",

					  (unsigned long long)le64_to_cpu(dx_root->dr_blkno),

					  le16_to_cpu(el->l_next_free_rec),

					  le16_to_cpu(el->l_count));

			goto bail;

		}

	}



bail:

	return ret;

}
@@ -791,14 +815,6 @@ static int ocfs2_dx_dir_lookup_rec(struct inode *inode, 
	struct ocfs2_extent_block *eb;

	struct ocfs2_extent_rec *rec = NULL;



	if (le16_to_cpu(el->l_count) !=

	    ocfs2_extent_recs_per_dx_root(inode->i_sb)) {

		ret = ocfs2_error(inode->i_sb,

				  "Inode %lu has invalid extent list length %u\n",

				  inode->i_ino, le16_to_cpu(el->l_count));

		goto out;

	}



	if (el->l_tree_depth) {

		ret = ocfs2_find_leaf(INODE_CACHE(inode), el, major_hash,

				      &eb_bh);