linux-kernel - [PATCH v2] ocfs2: Avoid NULL pointer dereference in dx_dir_lookup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250701023717.543972-1-ipravdin.official@gmail.com>
Date: Mon, 30 Jun 2025 22:37:17 -0400
From: Ivan Pravdin <ipravdin.official@...il.com>
To: mark@...heh.com,
	jlbec@...lplan.org,
	joseph.qi@...ux.alibaba.com,
	ocfs2-devel@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Ivan Pravdin <ipravdin.official@...il.com>,
	syzbot+20282c1b2184a857ac4c@...kaller.appspotmail.com
Subject: [PATCH v2] ocfs2: Avoid NULL pointer dereference in dx_dir_lookup_rec()

When a directory entry is not found, ocfs2_dx_dir_lookup_rec() prints an
error message that unconditionally dereferences the 'rec' pointer.
However, if 'rec' is NULL, this leads to a NULL pointer dereference and
a kernel panic.

Add an explicit check for a NULL 'rec' and use an alternate error
message in that case to avoid unsafe access.

Reported-by: syzbot+20282c1b2184a857ac4c@...kaller.appspotmail.com
Closes: https://lore.kernel.org/all/67cd7e29.050a0220.e1a89.0007.GAE@google.com/
Signed-off-by: Ivan Pravdin <ipravdin.official@...il.com>
---
v1 -> v2: Changed 'Closes:' tag to point to the correct bug report.

 fs/ocfs2/dir.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index 7799f4d16ce9..dccf0349e523 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -809,11 +809,17 @@ static int ocfs2_dx_dir_lookup_rec(struct inode *inode,
 	}
 
 	if (!found) {
-		ret = ocfs2_error(inode->i_sb,
-				  "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
-				  inode->i_ino,
-				  le32_to_cpu(rec->e_cpos),
-				  ocfs2_rec_clusters(el, rec));
+		if (rec) {
+			ret = ocfs2_error(inode->i_sb,
+					"Inode %lu has bad extent record (%u, %u, 0) in btree\n",
+					inode->i_ino,
+					le32_to_cpu(rec->e_cpos),
+					ocfs2_rec_clusters(el, rec));
+		} else {
+			ret = ocfs2_error(inode->i_sb,
+					"Inode %lu has no extent records in btree\n",
+					inode->i_ino);
+		}
 		goto out;
 	}
 
-- 
2.45.2