From: Kees Cook <keescook@chromium.org>
To: syzbot
<bot+2357afb48acb76780f3c18867ccfb7aa6fd6c4c9@syzkaller.appspotmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>, Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
syzkaller-bugs@googlegroups.com,
David Windsor <dave@nullcore.net>
Subject: Re: WARNING in __check_heap_object
Date: Tue, 7 Nov 2017 12:35:21 -0800 [thread overview]
Message-ID: <CAGXu5jJFwPYre6P2vf1v0XFBFfk-uqJEYEPP8WsjPspZoYDHCg@mail.gmail.com> (raw)
In-Reply-To: <001a114096fec09301055d68d784@google.com>
On Tue, Nov 7, 2017 at 10:36 AM, syzbot
<bot+2357afb48acb76780f3c18867ccfb7aa6fd6c4c9@syzkaller.appspotmail.com>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> 5a3517e009e979f21977d362212b7729c5165d92
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
>
>
Please include the line _before_ the "cut here" (dumb, I know, but
that's where warnings show up...)
Found in the raw.log:
[ 44.227177] unexpected usercopy without slab whitelist from SCTPv6
offset 1648 size 11
This means some part of the SCTPv6 slab was being poked into userspace
without a usercopy whitelist.
> check_heap_object mm/usercopy.c:222 [inline]
> __check_object_size+0x22c/0x4f0 mm/usercopy.c:248
> check_object_size include/linux/thread_info.h:112 [inline]
> check_copy_size include/linux/thread_info.h:143 [inline]
> copy_to_user include/linux/uaccess.h:154 [inline]
> sctp_getsockopt_events net/sctp/socket.c:4972 [inline]
> sctp_getsockopt+0x2b90/0x70b0 net/sctp/socket.c:7012
> sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2924
> SYSC_getsockopt net/socket.c:1882 [inline]
> SyS_getsockopt+0x178/0x340 net/socket.c:1864
> entry_SYSCALL_64_fastpath+0x1f/0xbe
Looking at the SCTPv6 slab declaration, it seems David and I missed
the usercopy whitelist for the sctpv6_sock struct. I'll update the
usercopy whitelist patch with:
#syz fix: sctp: Define usercopy region in SCTP proto slab cache
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 5fd83974c5cc..8ac85877c0e4 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8492,6 +8492,10 @@ struct proto sctpv6_prot = {
.unhash = sctp_unhash,
.get_port = sctp_get_port,
.obj_size = sizeof(struct sctp6_sock),
+ .useroffset = offsetof(struct sctp_sock, subscribe),
+ .usersize = offsetof(struct sctp_sock, initmsg) -
+ offsetof(struct sctp_sock, subscribe) +
+ sizeof_field(struct sctp_sock, initmsg),
.sysctl_mem = sysctl_sctp_mem,
.sysctl_rmem = sysctl_sctp_rmem,
.sysctl_wmem = sysctl_sctp_wmem,
Thanks!
-Kees
--
Kees Cook
Pixel Security
--
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next prev parent reply other threads:[~2017-11-07 20:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 18:36 WARNING in __check_heap_object syzbot
2017-11-07 19:34 ` Christopher Lameter
2017-11-07 20:35 ` Kees Cook [this message]
2017-11-08 8:23 ` Dmitry Vyukov
2017-11-08 19:02 ` Kees Cook
2017-11-08 19:08 ` Dmitry Vyukov
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