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Mon, 30 Jun 2025 19:37:39 -0700 (PDT) Received: from ipravd-Nitro-AN515-55.hsd1.ca.comcast.net ([2601:646:a000:5fc0:185e:4baa:85df:637]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b34e31db000sm9017202a12.65.2025.06.30.19.37.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Jun 2025 19:37:39 -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 v2] ocfs2: Avoid NULL pointer dereference in dx_dir_lookup_rec() Date: Mon, 30 Jun 2025 22:37:17 -0400 Message-ID: <20250701023717.543972-1-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 for a NULL 'rec' and use an alternate error message in that case to avoid unsafe access. 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 --- 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 *inod= e, } =20 if (!found) { - ret =3D 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 =3D 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 =3D ocfs2_error(inode->i_sb, + "Inode %lu has no extent records in btree\n", + inode->i_ino); + } goto out; } =20 --=20 2.45.2