From: Oleg Nesterov <oleg@redhat.com> To: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org>, Hector Marco-Gisbert <hecmargi@upv.es>, Ismael Ripoll Ripoll <iripoll@upv.es>, Alexander Viro <viro@zeniv.linux.org.uk>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Chen Gang <gang.chen.5i5j@gmail.com>, Michal Hocko <mhocko@suse.com>, Konstantin Khlebnikov <koct9i@gmail.com>, Andrea Arcangeli <aarcange@redhat.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 2/2] mm: refuse wrapped vm_brk requests Date: Tue, 12 Jul 2016 15:39:42 +0200 [thread overview] Message-ID: <20160712133942.GA28837@redhat.com> (raw) In-Reply-To: <CAGXu5j+efUrhOTikpuYK0V8Eqv58f5rQBMOYDqiVM-JWrqRbLA@mail.gmail.com> On 07/11, Kees Cook wrote: > > On Mon, Jul 11, 2016 at 8:28 AM, Oleg Nesterov <oleg@redhat.com> wrote: > > > > and thus this patch fixes the error code returned by do_brk() in case > > of overflow, now it returns -ENOMEM rather than zero. Perhaps > > > > if (!len) > > return 0; > > len = PAGE_ALIGN(len); > > if (!len) > > return -ENOMEM; > > > > would be more clear but this is subjective. > > I'm fine either way. Me too, so feel free to ignore, > > I am wondering if we should shift this overflow check to the caller(s). > > Say, sys_brk() does find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE) > > before do_brk(), and in case of overflow find_vma_intersection() can > > wrongly return NULL. > > > > Then do_brk() will be called with len = -oldbrk, this can overflow or > > not but in any case this doesn't look right too. > > > > Or I am totally confused? > > I think the callers shouldn't request a negative value, sure, but > vm_brk should notice and refuse it. Not sure I understand... I tried to say that, with or without this change, sys_brk() should check for overflow too, otherwise it looks buggy. Oleg.
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com> To: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org>, Hector Marco-Gisbert <hecmargi@upv.es>, Ismael Ripoll Ripoll <iripoll@upv.es>, Alexander Viro <viro@zeniv.linux.org.uk>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Chen Gang <gang.chen.5i5j@gmail.com>, Michal Hocko <mhocko@suse.com>, Konstantin Khlebnikov <koct9i@gmail.com>, Andrea Arcangeli <aarcange@redhat.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 2/2] mm: refuse wrapped vm_brk requests Date: Tue, 12 Jul 2016 15:39:42 +0200 [thread overview] Message-ID: <20160712133942.GA28837@redhat.com> (raw) In-Reply-To: <CAGXu5j+efUrhOTikpuYK0V8Eqv58f5rQBMOYDqiVM-JWrqRbLA@mail.gmail.com> On 07/11, Kees Cook wrote: > > On Mon, Jul 11, 2016 at 8:28 AM, Oleg Nesterov <oleg@redhat.com> wrote: > > > > and thus this patch fixes the error code returned by do_brk() in case > > of overflow, now it returns -ENOMEM rather than zero. Perhaps > > > > if (!len) > > return 0; > > len = PAGE_ALIGN(len); > > if (!len) > > return -ENOMEM; > > > > would be more clear but this is subjective. > > I'm fine either way. Me too, so feel free to ignore, > > I am wondering if we should shift this overflow check to the caller(s). > > Say, sys_brk() does find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE) > > before do_brk(), and in case of overflow find_vma_intersection() can > > wrongly return NULL. > > > > Then do_brk() will be called with len = -oldbrk, this can overflow or > > not but in any case this doesn't look right too. > > > > Or I am totally confused? > > I think the callers shouldn't request a negative value, sure, but > vm_brk should notice and refuse it. Not sure I understand... I tried to say that, with or without this change, sys_brk() should check for overflow too, otherwise it looks buggy. Oleg. -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-07-12 13:39 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-08 21:48 [PATCH 0/2] binfmt_elf: fix calculations for bss padding Kees Cook 2016-07-08 21:48 ` Kees Cook 2016-07-08 21:48 ` [PATCH 1/2] " Kees Cook 2016-07-08 21:48 ` Kees Cook 2016-07-12 22:32 ` Kees Cook 2016-07-12 22:32 ` Kees Cook 2016-07-08 21:48 ` [PATCH 2/2] mm: refuse wrapped vm_brk requests Kees Cook 2016-07-08 21:48 ` Kees Cook 2016-07-11 12:28 ` Oleg Nesterov 2016-07-11 12:28 ` Oleg Nesterov 2016-07-11 18:01 ` Kees Cook 2016-07-11 18:01 ` Kees Cook 2016-07-12 13:39 ` Oleg Nesterov [this message] 2016-07-12 13:39 ` Oleg Nesterov 2016-07-12 17:15 ` Kees Cook 2016-07-12 17:15 ` Kees Cook 2016-07-13 17:00 ` Oleg Nesterov 2016-07-13 17:00 ` Oleg Nesterov
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