From patchwork Fri Jan 31 06:11:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 232295 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FB89C33CB2 for ; Fri, 31 Jan 2020 06:11:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59C5E22522 for ; Fri, 31 Jan 2020 06:11:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580451069; bh=vpsxjURaJ+1tZ+ToK+fDX7WaU2fULE0P/OkFaMA6/Nk=; h=Date:From:To:Subject:In-Reply-To:List-ID:From; b=OIa9B9SponY6ySP0KZhLI40gy2mkYrTW9ZKhH4Lduh+/e+YGuGGbcL12LWBKS1JF0 mEwI7C5y1dj+388EA4vF3hBzNw0KTELniBCUzodhdDzvn+IcNOipiBJY7ihVgN/u44 /K5ISRdRFS6gy3g7Ercgq6Ps2hOcQrezjkZDdTRw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728076AbgAaGLJ (ORCPT ); Fri, 31 Jan 2020 01:11:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:57924 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725907AbgAaGLI (ORCPT ); Fri, 31 Jan 2020 01:11:08 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 098DD21734; Fri, 31 Jan 2020 06:11:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580451068; bh=vpsxjURaJ+1tZ+ToK+fDX7WaU2fULE0P/OkFaMA6/Nk=; h=Date:From:To:Subject:In-Reply-To:From; b=x0XEz+KGL42PVjPAASfmn1uoCzF3aX+X0XwYw4621SX/LqZ/TzjEkNtzAEtgtZ6UR XW7OHC2/Se2VQEr1tsYSAP//p7G6rO0EDLlsjc26aqDNuFFDJeH8XLxphfVR0CG00s bijqsGHZrakyI0fXWqSLjhOU0/y0GOFjHq052gl0= Date: Thu, 30 Jan 2020 22:11:07 -0800 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, dan.carpenter@oracle.com, hughd@google.com, lee.schermerhorn@hp.com, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 003/118] mm/mempolicy.c: fix out of bounds write in mpol_parse_str() Message-ID: <20200131061107.US9oQYBpA%akpm@linux-foundation.org> In-Reply-To: <20200130221021.5f0211c56346d5485af07923@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dan Carpenter Subject: mm/mempolicy.c: fix out of bounds write in mpol_parse_str() What we are trying to do is change the '=' character to a NUL terminator and then at the end of the function we restore it back to an '='. The problem is there are two error paths where we jump to the end of the function before we have replaced the '=' with NUL. We end up putting the '=' in the wrong place (possibly one element before the start of the buffer). Link: http://lkml.kernel.org/r/20200115055426.vdjwvry44nfug7yy@kili.mountain Reported-by: syzbot+e64a13c5369a194d67df@syzkaller.appspotmail.com Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display") Signed-off-by: Dan Carpenter Acked-by: Vlastimil Babka Dmitry Vyukov Cc: Michal Hocko Cc: Dan Carpenter Cc: Lee Schermerhorn Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Signed-off-by: Andrew Morton --- mm/mempolicy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/mempolicy.c~mm-mempolicyc-fix-out-of-bounds-write-in-mpol_parse_str +++ a/mm/mempolicy.c @@ -2821,6 +2821,9 @@ int mpol_parse_str(char *str, struct mem char *flags = strchr(str, '='); int err = 1, mode; + if (flags) + *flags++ = '\0'; /* terminate mode string */ + if (nodelist) { /* NUL-terminate mode or flags string */ *nodelist++ = '\0'; @@ -2831,9 +2834,6 @@ int mpol_parse_str(char *str, struct mem } else nodes_clear(nodes); - if (flags) - *flags++ = '\0'; /* terminate mode string */ - mode = match_string(policy_modes, MPOL_MAX, str); if (mode < 0) goto out;