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Mon, 07 Jul 2025 17:11:01 -0700 (PDT) Received: from ipravd-Nitro-AN515-55.hsd1.ca.comcast.net ([2601:646:a000:5fc0:268b:48b1:88cf:6e90]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23c845bd366sm102928615ad.240.2025.07.07.17.11.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Jul 2025 17:11:01 -0700 (PDT) From: Ivan Pravdin To: mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Ivan Pravdin , syzbot+20282c1b2184a857ac4c@syzkaller.appspotmail.com Subject: [PATCH v3] ocfs2: Avoid NULL pointer dereference in dx_dir_lookup_rec() Date: Mon, 7 Jul 2025 20:10:09 -0400 Message-ID: <20250708001009.372263-1-ipravdin.official@gmail.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 empty extent list to avoid dereferencing NULL 'rec' pointer. Reported-by: syzbot+20282c1b2184a857ac4c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67cd7e29.050a0220.e1a89.0007.GAE@google= .com/ Signed-off-by: Ivan Pravdin Reviewed-by: Joseph Qi --- v1 -> v2: Changed 'Closes:' tag to point to the correct bug report. v2 -> v3: Added an explicit check for empty extent list before dereferencin= g 'rec'. fs/ocfs2/dir.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c index 7799f4d16ce9..acbae902ae3a 100644 --- a/fs/ocfs2/dir.c +++ b/fs/ocfs2/dir.c @@ -798,6 +798,14 @@ static int ocfs2_dx_dir_lookup_rec(struct inode *inode, } } =20 + if (le16_to_cpu(el->l_next_free_rec) =3D=3D 0) { + ret =3D ocfs2_error(inode->i_sb, + "Inode %lu has empty extent list at depth %u\n", + inode->i_ino,=20 + le16_to_cpu(el->l_tree_depth)); + goto out; + } + found =3D 0; for (i =3D le16_to_cpu(el->l_next_free_rec) - 1; i >=3D 0; i--) { rec =3D &el->l_recs[i]; --=20 2.45.2