From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752331AbeBKCqk (ORCPT ); Sat, 10 Feb 2018 21:46:40 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751087AbeBKCqi (ORCPT ); Sat, 10 Feb 2018 21:46:38 -0500 Subject: Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE To: Eric Biggers Cc: mst@redhat.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org References: <1518169550-5987-1-git-send-email-jasowang@redhat.com> <20180210193201.GB23737@zzz.localdomain> From: Jason Wang Message-ID: <322ed04e-2bc2-0453-cd10-8d7784a8eb38@redhat.com> Date: Sun, 11 Feb 2018 10:46:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20180210193201.GB23737@zzz.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018年02月11日 03:32, Eric Biggers wrote: > Hi Jason, > > On Fri, Feb 09, 2018 at 05:45:49PM +0800, Jason Wang wrote: >> To avoid slab to warn about exceeded size, fail early if queue >> occupies more than KMALLOC_MAX_SIZE. >> >> Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com >> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers") >> Signed-off-by: Jason Wang >> --- >> include/linux/ptr_ring.h | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h >> index 1883d61..6051a5f 100644 >> --- a/include/linux/ptr_ring.h >> +++ b/include/linux/ptr_ring.h >> @@ -466,6 +466,8 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r, >> >> static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp) >> { >> + if (size * sizeof(void *) > KMALLOC_MAX_SIZE) >> + return NULL; > Are you sure that size can't be over 0x40000000? The proper way to write this > (safe from integer overflow) would be: > > if (size > KMALLOC_MAX_SIZE / sizeof(void *)) > return NULL; > > - Eric Good catch. Will post a fix. Thanks