From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f44.google.com (mail-ee0-f44.google.com [74.125.83.44]) by kanga.kvack.org (Postfix) with ESMTP id 2AB176B0070 for ; Wed, 23 Apr 2014 01:05:54 -0400 (EDT) Received: by mail-ee0-f44.google.com with SMTP id e49so291635eek.31 for ; Tue, 22 Apr 2014 22:05:53 -0700 (PDT) Received: from mail-ee0-x22b.google.com (mail-ee0-x22b.google.com [2a00:1450:4013:c00::22b]) by mx.google.com with ESMTPS id d5si1306663eei.148.2014.04.22.22.05.52 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 22 Apr 2014 22:05:52 -0700 (PDT) Received: by mail-ee0-f43.google.com with SMTP id e53so287710eek.16 for ; Tue, 22 Apr 2014 22:05:52 -0700 (PDT) Message-ID: <53574888.4090602@gmail.com> Date: Wed, 23 Apr 2014 06:58:48 +0200 From: "Michael Kerrisk (man-pages)" MIME-Version: 1.0 Subject: Re: [PATCH 2/4] ipc/shm.c: check for overflows of shm_tot References: <1398090397-2397-1-git-send-email-manfred@colorfullife.com> <1398090397-2397-2-git-send-email-manfred@colorfullife.com> <1398090397-2397-3-git-send-email-manfred@colorfullife.com> In-Reply-To: <1398090397-2397-3-git-send-email-manfred@colorfullife.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Manfred Spraul , Davidlohr Bueso , Martin Schwidefsky Cc: mtk.manpages@gmail.com, LKML , Andrew Morton , KAMEZAWA Hiroyuki , KOSAKI Motohiro , gthelen@google.com, aswin@hp.com, linux-mm@kvack.org On 04/21/2014 04:26 PM, Manfred Spraul wrote: > shm_tot counts the total number of pages used by shm segments. > > If SHMALL is ULONG_MAX (or nearly ULONG_MAX), then the number > can overflow. Subsequent calls to shmctl(,SHM_INFO,) would return > wrong values for shm_tot. > > The patch adds a detection for overflows. > > Signed-off-by: Manfred Spraul > --- > ipc/shm.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/ipc/shm.c b/ipc/shm.c > index 382e2fb..2dfa3d6 100644 > --- a/ipc/shm.c > +++ b/ipc/shm.c > @@ -493,7 +493,8 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) > if (size < SHMMIN || size > ns->shm_ctlmax) > return -EINVAL; > > - if (ns->shm_tot + numpages > ns->shm_ctlall) > + if (ns->shm_tot + numpages < ns->shm_tot || > + ns->shm_tot + numpages > ns->shm_ctlall) > return -ENOSPC; > > shp = ipc_rcu_alloc(sizeof(*shp)); > Acked-by: Michael Kerrisk -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org