linux-kernel - [PATCH 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find

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Date: Wed, 15 May 2024 21:29:34 +0800
From: Ferry Meng <mengferry@...ux.alibaba.com>
To: Mark Fasheh <mark@...heh.com>,
	Joel Becker <jlbec@...lplan.org>,
	Joseph Qi <joseph.qi@...ux.alibaba.com>,
	ocfs2-devel@...ts.linux.dev
Cc: linux-kernel@...r.kernel.org,
	Ferry Meng <mengferry@...ux.alibaba.com>
Subject: [PATCH 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry()

xattr in ocfs2 maybe not INLINE, but saved with additional space
requested. It's better to check if the memory is out of bound before
memcmp, although this possibility mainly comes from custom poisonous
images.

Signed-off-by: Ferry Meng <mengferry@...ux.alibaba.com>
---
 fs/ocfs2/xattr.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 37be4a286faf..4ceb0cb4cb71 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -1083,10 +1083,15 @@ static int ocfs2_xattr_find_entry(struct inode *inode, void *end,
 		cmp = name_index - ocfs2_xattr_get_type(entry);
 		if (!cmp)
 			cmp = name_len - entry->xe_name_len;
-		if (!cmp)
+		if (!cmp) {
+			if ((xs->base + le16_to_cpu(entry->xe_name_offset) + name_len) > end) {
+				ocfs2_error(inode->i_sb, "corrupted xattr entries");
+				return -EFSCORRUPTED;
+			}
 			cmp = memcmp(name, (xs->base +
 				     le16_to_cpu(entry->xe_name_offset)),
 				     name_len);
+		}
 		if (cmp == 0)
 			break;
 		entry += 1;
-- 
2.32.0.3.g01195cf9f