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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 8D834C31E4B for ; Fri, 14 Jun 2019 11:50:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 618E120850 for ; Fri, 14 Jun 2019 11:50:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="E7ZP9j9Y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727517AbfFNLuj (ORCPT ); Fri, 14 Jun 2019 07:50:39 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:36808 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727217AbfFNLuj (ORCPT ); Fri, 14 Jun 2019 07:50:39 -0400 Received: by mail-pg1-f195.google.com with SMTP id f21so1433768pgi.3; Fri, 14 Jun 2019 04:50:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=h3a8MSgllR1VzyxCgXzslXCSIaES75ArkXEmitqW5jU=; b=E7ZP9j9YWgo8vSuFABpgNgE2+vhludF3mH8n5M6tO78o+s0p7B3iAj+j/R0jY63w1n qIpEMPj6OPQjKTSyzol3TEvGbco7cyOADqeWZh1Iaec6DMeaJLP5C8AyjIjPvlSjFsRG Ysw4b5XIU4WUbm1/onI39AHEqLFrsb2shYhe9jgfYBV2SpJe8D1/wSjD5BHOPqltyob1 3hGQGZWyPZmCKKnnaSZ4JUXya08IQ/kdLH/qerOr8lOL0/ytZtUnOH24YouPKFC8oGX+ FBOxARwmP1qy7VDbZDqWqR8lXP+gK0N3X3nkmNkWaZ0haF1uZb0tIajrCEG48d3SD7e+ hlKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=h3a8MSgllR1VzyxCgXzslXCSIaES75ArkXEmitqW5jU=; b=Vck6FDiiofYqL6ODDucD+B/kjukPau4y5qtkJCkBlokbwPpMvFBClJoir3Ea+hPl/O v9+F/T9aSx735ZKlHyEPkc5+yLy7ZrGqYn9qhnt7b+nhJUQrNXWdEpZHeZwPAVdR1Ttr Juh/HDtCUHMynfImJnc7g5mGGfSkbA+X4zV7UWb315wvYyJNai5hw2djGLpWFJhYSa4o mAo1SkGFl2E9b2SZH6+D/c19xjnm+Z8LTBsx21TS6TgAo3rmMR5qUOgGXnSwUJ7ediA0 ADOE24cojOOY20fCIPQ5R0ZmtGa/Cs375PKHmZ8zAsr0RTRqViuMsSqj6nPeEi3QrP+r WdlA== X-Gm-Message-State: APjAAAWUrjHEyLwPIVQIu2+3cCUqFj+kqta1ZI1LGn5yaVmpebdosjyf ntm9Hl2EUerQZ4lHha726V30GsBe3t6adA== X-Google-Smtp-Source: APXvYqxlEHvwEzPSNOgpEmqYxAwFljTQCNczS9YEeJvwU1v3jnZxJfJTHERdfqNnMhb0CS1KegTDlQ== X-Received: by 2002:a63:6105:: with SMTP id v5mr35288809pgb.312.1560513038336; Fri, 14 Jun 2019 04:50:38 -0700 (PDT) Received: from xy-data.openstacklocal ([159.138.22.150]) by smtp.gmail.com with ESMTPSA id f10sm2275556pgq.73.2019.06.14.04.50.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 14 Jun 2019 04:50:37 -0700 (PDT) From: Young Xiao <92siuyang@gmail.com> To: clm@fb.com, josef@toxicpanda.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Young Xiao <92siuyang@gmail.com> Subject: [PATCH] btrfs: fix out of bounds array access while reading extent buffer Date: Fri, 14 Jun 2019 19:51:49 +0800 Message-Id: <1560513109-2568-1-git-send-email-92siuyang@gmail.com> X-Mailer: git-send-email 2.7.4 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org There is a corner case that slips through the checkers in functions reading extent buffer, ie. if (start < eb->len) and (start + len > eb->len), then: the checkers in read_extent_buffer_to_user(), and memcmp_extent_buffer() WARN_ON(start > eb->len) and WARN_ON(start + len > eb->start + eb->len), both are OK in this corner case, but it'd actually try to access the eb->pages out of bounds because of (start + len > eb->len). This is adding proper checks in order to avoid invalid memory access, ie. 'general protection fault', before it's too late. See commit f716abd55d1e ("Btrfs: fix out of bounds array access while reading extent buffer") for details. Signed-off-by: Young Xiao <92siuyang@gmail.com> --- fs/btrfs/extent_io.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index db337e5..dcf3b2e 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5476,8 +5476,12 @@ int read_extent_buffer_to_user(const struct extent_buffer *eb, unsigned long i = (start_offset + start) >> PAGE_SHIFT; int ret = 0; - WARN_ON(start > eb->len); - WARN_ON(start + len > eb->start + eb->len); + if (start + len > eb->len) { + WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n", + eb->start, eb->len, start, len); + memset(dst, 0, len); + return; + } offset = offset_in_page(start_offset + start); @@ -5554,8 +5558,12 @@ int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv, unsigned long i = (start_offset + start) >> PAGE_SHIFT; int ret = 0; - WARN_ON(start > eb->len); - WARN_ON(start + len > eb->start + eb->len); + if (start + len > eb->len) { + WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n", + eb->start, eb->len, start, len); + memset(ptr, 0, len); + return; + } offset = offset_in_page(start_offset + start); -- 2.7.4