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Wed, 29 Sep 2021 20:07:33 +0200 (CEST) From: Valentin Vidic To: Joseph Qi Date: Wed, 29 Sep 2021 20:06:54 +0200 Message-Id: <20210929180654.32460-1-vvidic@valentin-vidic.from.hr> X-Mailer: git-send-email 2.20.1 In-Reply-To: <1ab61ba3-8c9b-092c-7843-9c45b58e3987@linux.alibaba.com> References: <1ab61ba3-8c9b-092c-7843-9c45b58e3987@linux.alibaba.com> MIME-Version: 1.0 X-Source-IP: 109.200.23.17 X-ServerName: valentin-vidic.from.hr X-Proofpoint-SPF-Result: pass X-Proofpoint-SPF-Record: v=spf1 mx -all X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10122 signatures=668683 X-Proofpoint-Spam-Details: rule=tap_notspam policy=tap score=0 clxscore=284 priorityscore=0 suspectscore=0 spamscore=0 malwarescore=0 bulkscore=0 mlxlogscore=999 impostorscore=0 mlxscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2109290104 X-Spam: Clean X-Mailman-Approved-At: Wed, 29 Sep 2021 11:58:19 -0700 Cc: Valentin Vidic , ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org Subject: [Ocfs2-devel] [PATCH v2] ocfs2: mount fails with buffer overflow in strlen X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10122 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 mlxscore=0 mlxlogscore=999 phishscore=0 bulkscore=0 suspectscore=0 malwarescore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2109290110 X-Proofpoint-GUID: zHOq0VSWL4G26H4AFxOwR9ExCxRIDoSL X-Proofpoint-ORIG-GUID: zHOq0VSWL4G26H4AFxOwR9ExCxRIDoSL Starting with kernel 5.11 built with CONFIG_FORTIFY_SOURCE mouting an ocfs2 filesystem with either o2cb or pcmk cluster stack fails with the trace below. Problem seems to be that strings for cluster stack and cluster name are not guaranteed to be null terminated in the disk representation, while strlcpy assumes that the source string is always null terminated. This causes a read outside of the source string triggering the buffer overflow detection. detected buffer overflow in strlen ------------[ cut here ]------------ kernel BUG at lib/string.c:1149! invalid opcode: 0000 [#1] SMP PTI CPU: 1 PID: 910 Comm: mount.ocfs2 Not tainted 5.14.0-1-amd64 #1 Debian 5.14.6-2 RIP: 0010:fortify_panic+0xf/0x11 ... Call Trace: ocfs2_initialize_super.isra.0.cold+0xc/0x18 [ocfs2] ocfs2_fill_super+0x359/0x19b0 [ocfs2] mount_bdev+0x185/0x1b0 ? ocfs2_remount+0x440/0x440 [ocfs2] legacy_get_tree+0x27/0x40 vfs_get_tree+0x25/0xb0 path_mount+0x454/0xa20 __x64_sys_mount+0x103/0x140 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae Signed-off-by: Valentin Vidic Reviewed-by: Joseph Qi --- v2: update description, add comment, drop null termination fs/ocfs2/super.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c index c86bd4e60e20..5c914ce9b3ac 100644 --- a/fs/ocfs2/super.c +++ b/fs/ocfs2/super.c @@ -2167,11 +2167,17 @@ static int ocfs2_initialize_super(struct super_block *sb, } if (ocfs2_clusterinfo_valid(osb)) { + /* + * ci_stack and ci_cluster in ocfs2_cluster_info may not be null + * terminated, so make sure no overflow happens here by using + * memcpy. Destination strings will always be null terminated + * because osb is allocated using kzalloc. + */ osb->osb_stackflags = OCFS2_RAW_SB(di)->s_cluster_info.ci_stackflags; - strlcpy(osb->osb_cluster_stack, + memcpy(osb->osb_cluster_stack, OCFS2_RAW_SB(di)->s_cluster_info.ci_stack, - OCFS2_STACK_LABEL_LEN + 1); + OCFS2_STACK_LABEL_LEN); if (strlen(osb->osb_cluster_stack) != OCFS2_STACK_LABEL_LEN) { mlog(ML_ERROR, "couldn't mount because of an invalid " @@ -2180,9 +2186,9 @@ static int ocfs2_initialize_super(struct super_block *sb, status = -EINVAL; goto bail; } - strlcpy(osb->osb_cluster_name, + memcpy(osb->osb_cluster_name, OCFS2_RAW_SB(di)->s_cluster_info.ci_cluster, - OCFS2_CLUSTER_NAME_LEN + 1); + OCFS2_CLUSTER_NAME_LEN); } else { /* The empty string is identical with classic tools that * don't know about s_cluster_info. */