From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753902AbeBFXVw (ORCPT ); Tue, 6 Feb 2018 18:21:52 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:47796 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753673AbeBFXVu (ORCPT ); Tue, 6 Feb 2018 18:21:50 -0500 Date: Tue, 6 Feb 2018 15:21:48 -0800 From: Andrew Morton To: syzbot Cc: adobriyan@gmail.com, arnd@arndb.de, dave.jiang@intel.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, David Rientjes Subject: Re: WARNING: kmalloc bug in relay_open_buf Message-Id: <20180206152148.bfe7464fe12452d60ec91209@linux-foundation.org> In-Reply-To: <001a113ecb5e596b8e0564931c04@google.com> References: <001a113ecb5e596b8e0564931c04@google.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 06 Feb 2018 14:58:02 -0800 syzbot wrote: > Hello, > > syzbot hit the following crash on upstream commit > e237f98a9c134c3d600353f21e07db915516875b (Mon Feb 5 21:35:56 2018 +0000) > Merge tag 'xfs-4.16-merge-5' of > git://git.kernel.org/pub/scm/fs/xfs/xfs-linux > > C reproducer is attached. > syzkaller reproducer is attached. > Raw console output is attached. > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+7525b19f9531f76b8b1e@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > audit: type=1400 audit(1517939984.452:7): avc: denied { map } for > pid=4159 comm="syzkaller032522" path="/root/syzkaller032522586" dev="sda1" > ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 > tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 > WARNING: CPU: 0 PID: 4159 at mm/slab_common.c:1012 kmalloc_slab+0x5d/0x70 > mm/slab_common.c:1012 > Kernel panic - not syncing: panic_on_warn set ... David sent a fix today which I believe will address this. From: David Rientjes Subject: kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE chan->n_subbufs is set by the user and relay_create_buf() does a kmalloc() of chan->n_subbufs * sizeof(size_t *). kmalloc_slab() will generate a warning when this fails if chan->subbufs * sizeof(size_t *) > KMALLOC_MAX_SIZE. Limit chan->n_subbufs to the maximum allowed kmalloc() size. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802061216100.122576@chino.kir.corp.google.com Fixes: f6302f1bcd75 ("relay: prevent integer overflow in relay_open()") Signed-off-by: David Rientjes Reviewed-by: Andrew Morton Cc: Jens Axboe Cc: Dave Jiang Cc: Al Viro Cc: Dan Carpenter Signed-off-by: Andrew Morton --- kernel/relay.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/relay.c~kernel-relay-limit-kmalloc-size-to-kmalloc_max_size kernel/relay.c --- a/kernel/relay.c~kernel-relay-limit-kmalloc-size-to-kmalloc_max_size +++ a/kernel/relay.c @@ -163,7 +163,7 @@ static struct rchan_buf *relay_create_bu { struct rchan_buf *buf; - if (chan->n_subbufs > UINT_MAX / sizeof(size_t *)) + if (chan->n_subbufs > KMALLOC_MAX_SIZE / sizeof(size_t *)) return NULL; buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); _