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=-6.8 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,USER_AGENT_GIT autolearn=ham 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 C5D6AC35249 for ; Mon, 3 Feb 2020 16:20:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9898B20CC7 for ; Mon, 3 Feb 2020 16:20:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580746840; bh=UlhBxJ78W/uvMNsytpxoAbV/PPJsttRUazpMtceXIXo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=wAcOh4p+PaoEjFqiB6L9AEeV/zjW+yRsUCtBYnNdlkfXemDHHJe/6R/gzGL2zIvEi hJdOGNpW9LpPyrRaa+Wm7oM4EsAoxdo9GWflx8puV4NVJON60WdOKo36KVIDmrQ42d yjTu1UBnnrBMekRN45t235xXRXtyODALGqMb3T2E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728493AbgBCQUj (ORCPT ); Mon, 3 Feb 2020 11:20:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:60440 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728486AbgBCQUg (ORCPT ); Mon, 3 Feb 2020 11:20:36 -0500 Received: from localhost (unknown [104.132.45.99]) (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 27DFA20838; Mon, 3 Feb 2020 16:20:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580746835; bh=UlhBxJ78W/uvMNsytpxoAbV/PPJsttRUazpMtceXIXo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zz9D4OHnaRR5O+mg/dOSKoZFgg6RiatpMLL8MxKcAl/4OxNpkNlmytZ7vPNg/KxJ1 7y+zHofWrbZMs1Ui/41eWxPESAelvCdVarga/z0a+lCh2Om0QcQe8AFIB1Hx6tGK6z 03zJL5IvijXQArEuSNTrxUvZefYm6i3OUuqrxGwQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+e64a13c5369a194d67df@syzkaller.appspotmail.com, Dan Carpenter , Vlastimil Babka , Michal Hocko , Lee Schermerhorn , Andrea Arcangeli , Hugh Dickins , Andrew Morton , Linus Torvalds Subject: [PATCH 4.4 26/53] mm/mempolicy.c: fix out of bounds write in mpol_parse_str() Date: Mon, 3 Feb 2020 16:19:18 +0000 Message-Id: <20200203161907.906583720@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200203161902.714326084@linuxfoundation.org> References: <20200203161902.714326084@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dan Carpenter commit c7a91bc7c2e17e0a9c8b9745a2cb118891218fd1 upstream. 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 Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/mempolicy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2701,6 +2701,9 @@ int mpol_parse_str(char *str, struct mem char *flags = strchr(str, '='); int err = 1; + if (flags) + *flags++ = '\0'; /* terminate mode string */ + if (nodelist) { /* NUL-terminate mode or flags string */ *nodelist++ = '\0'; @@ -2711,9 +2714,6 @@ int mpol_parse_str(char *str, struct mem } else nodes_clear(nodes); - if (flags) - *flags++ = '\0'; /* terminate mode string */ - for (mode = 0; mode < MPOL_MAX; mode++) { if (!strcmp(str, policy_modes[mode])) { break;