From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932191AbeBKWCd (ORCPT ); Sun, 11 Feb 2018 17:02:33 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47644 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753503AbeBKWCc (ORCPT ); Sun, 11 Feb 2018 17:02:32 -0500 Date: Mon, 12 Feb 2018 00:02:31 +0200 From: "Michael S. Tsirkin" To: Jason Wang Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ebiggers3@gmail.com Subject: Re: [PATCH net] ptr_ring: prevent integer overflow when calculating size Message-ID: <20180212000219-mutt-send-email-mst@kernel.org> References: <1518319692-5421-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1518319692-5421-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 11, 2018 at 11:28:12AM +0800, Jason Wang wrote: > Switch to use dividing to prevent integer overflow when size is too > big to calculate allocation size properly. > > Reported-by: Eric Biggers > Fixes: 6e6e41c31122 ("ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE") > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin > --- > include/linux/ptr_ring.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h > index b884b77..e633522 100644 > --- a/include/linux/ptr_ring.h > +++ b/include/linux/ptr_ring.h > @@ -469,7 +469,7 @@ 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) > + if (size > KMALLOC_MAX_SIZE / sizeof(void *)) > return NULL; > return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO); > } > -- > 2.7.4