[PATCH 4/5] ocfs2: validate inline xattr header before inline refcount attach

[ZhengYuan Huang <gality369@gmail.com>]

[BUG]
A corrupt inline xattr header can make ocfs2_xattr_inline_attach_refcount()
feed an unchecked header into the refcount-attachment walk for inline
xattr values.

[CAUSE]
The inline refcount-attach path still derived the header directly from
di->i_xattr_inline_size and then passed it to code that iterates xh_count
and xattr entries.

[FIX]
Use the shared ibody header helper before attaching refcounts to inline
xattr values so corrupt header geometry is rejected with -EFSCORRUPTED
instead of being traversed.

Signed-off-by: ZhengYuan Huang <gality369@gmail.com>
---
 fs/ocfs2/xattr.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index bbb25a01b097..4877406a83ce 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -6016,14 +6016,17 @@ static int ocfs2_xattr_inline_attach_refcount(struct inode *inode,
 				struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)fe_bh->b_data;
-	struct ocfs2_xattr_header *header = (struct ocfs2_xattr_header *)
-				(fe_bh->b_data + inode->i_sb->s_blocksize -
-				le16_to_cpu(di->i_xattr_inline_size));
+	struct ocfs2_xattr_header *header;
+	int ret;
 	struct ocfs2_xattr_value_buf vb = {
 		.vb_bh = fe_bh,
 		.vb_access = ocfs2_journal_access_di,
 	};
 
+	ret = ocfs2_xattr_ibody_lookup_header(inode, di, &header);
+	if (ret)
+		return ret;
+
 	return ocfs2_xattr_attach_refcount_normal(inode, &vb, header,
 						  ref_ci, ref_root_bh, dealloc);
 }
-- 
2.43.0