All of lore.kernel.org
 help / color / mirror / Atom feed
From: Valentin Vidic <vvidic@valentin-vidic.from.hr>
To: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>, Joel Becker <jlbec@evilplan.org>,
	ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org,
	Valentin Vidic <vvidic@valentin-vidic.from.hr>
Subject: [PATCH v2] ocfs2: mount fails with buffer overflow in strlen
Date: Wed, 29 Sep 2021 20:06:54 +0200	[thread overview]
Message-ID: <20210929180654.32460-1-vvidic@valentin-vidic.from.hr> (raw)
In-Reply-To: <1ab61ba3-8c9b-092c-7843-9c45b58e3987@linux.alibaba.com>

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 <vvidic@valentin-vidic.from.hr>
---
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. */
-- 
2.30.2


WARNING: multiple messages have this Message-ID (diff)
From: Valentin Vidic <vvidic@valentin-vidic.from.hr>
To: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Valentin Vidic <vvidic@valentin-vidic.from.hr>,
	ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org
Subject: [Ocfs2-devel] [PATCH v2] ocfs2: mount fails with buffer overflow in strlen
Date: Wed, 29 Sep 2021 20:06:54 +0200	[thread overview]
Message-ID: <20210929180654.32460-1-vvidic@valentin-vidic.from.hr> (raw)
In-Reply-To: <1ab61ba3-8c9b-092c-7843-9c45b58e3987@linux.alibaba.com>

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 <vvidic@valentin-vidic.from.hr>
---
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. */
-- 
2.30.2


_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel

  reply	other threads:[~2021-09-29 18:07 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 15:44 [PATCH] ocfs2: mount fails with buffer overflow in strlen Valentin Vidic
2021-09-27 15:44 ` [Ocfs2-devel] " Valentin Vidic
2021-09-28 12:05 ` Joseph Qi
2021-09-28 12:05   ` [Ocfs2-devel] " Joseph Qi
2021-09-28 13:14   ` Valentin Vidić
2021-09-28 13:14     ` [Ocfs2-devel] " Valentin Vidić
2021-09-29  2:38     ` Joseph Qi
2021-09-29  2:38       ` [Ocfs2-devel] " Joseph Qi
2021-09-29  6:24       ` Valentin Vidić
2021-09-29  6:24         ` [Ocfs2-devel] " Valentin Vidić
2021-09-29  9:12         ` Joseph Qi
2021-09-29  9:12           ` [Ocfs2-devel] " Joseph Qi
2021-09-29 18:06           ` Valentin Vidic [this message]
2021-09-29 18:06             ` [Ocfs2-devel] [PATCH v2] " Valentin Vidic
2021-09-30  1:54             ` Joseph Qi
2021-09-30  1:54               ` [Ocfs2-devel] " Joseph Qi
2021-10-08 10:46               ` Gang He

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210929180654.32460-1-vvidic@valentin-vidic.from.hr \
    --to=vvidic@valentin-vidic.from.hr \
    --cc=jlbec@evilplan.org \
    --cc=joseph.qi@linux.alibaba.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark@fasheh.com \
    --cc=ocfs2-devel@oss.oracle.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.