From mboxrd@z Thu Jan 1 00:00:00 1970 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 9FC2EC33CB7 for ; Fri, 31 Jan 2020 06:11:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 65A35206A2 for ; Fri, 31 Jan 2020 06:11:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="x0XEz+KG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 65A35206A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 179BC6B04C2; Fri, 31 Jan 2020 01:11:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 12DA76B04C3; Fri, 31 Jan 2020 01:11:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 017696B04C4; Fri, 31 Jan 2020 01:11:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0151.hostedemail.com [216.40.44.151]) by kanga.kvack.org (Postfix) with ESMTP id DE40D6B04C2 for ; Fri, 31 Jan 2020 01:11:09 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8B6B32C0C for ; Fri, 31 Jan 2020 06:11:09 +0000 (UTC) X-FDA: 76436906658.20.sink26_a14857ad3d59 X-HE-Tag: sink26_a14857ad3d59 X-Filterd-Recvd-Size: 3343 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Fri, 31 Jan 2020 06:11:09 +0000 (UTC) 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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; _