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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 ABEF3C433E1 for ; Wed, 19 Aug 2020 06:36:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 965C1207DA for ; Wed, 19 Aug 2020 06:36:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726730AbgHSGgB (ORCPT ); Wed, 19 Aug 2020 02:36:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:59194 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726750AbgHSGf6 (ORCPT ); Wed, 19 Aug 2020 02:35:58 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 59EAEAEB1; Wed, 19 Aug 2020 06:36:23 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: Josef Bacik Subject: [PATCH v5 1/4] btrfs: extent_io: do extra check for extent buffer read write functions Date: Wed, 19 Aug 2020 14:35:47 +0800 Message-Id: <20200819063550.62832-2-wqu@suse.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200819063550.62832-1-wqu@suse.com> References: <20200819063550.62832-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Although we have start, len check for extent buffer reader/write (e.g. read_extent_buffer()), those checks has its limitations: - No overflow check Values like start = 1024 len = -1024 can still pass the basic (start + len) > eb->len check. - Checks are not consistent For read_extent_buffer() we only check (start + len) against eb->len. While for memcmp_extent_buffer() we also check start against eb->len. - Different error reporting mechanism We use WARN() in read_extent_buffer() but BUG() in memcpy_extent_buffer(). - Still modify memory if the request is obviously wrong In read_extent_buffer() even we find (start + len) > eb->len, we still call memset(dst, 0, len), which can eaisly cause memory access error if start + len overflows. To address above problems, this patch creates a new common function to check such access, check_eb_range(). - Add overflow check This function checks start, start + len against eb->len and overflow check. - Unified checks - Unified error reports Will call WARN() if CONFIG_BTRFS_DEBUG is configured. And also do btrfs_warn() message for non-debug build. - Exit ASAP if check fails No more possible memory corruption. - Add extra comment for @start @len used in those functions Even experienced developers sometimes get confused with the @start @len with logical address in those functions. I'm not sure what's the cause, maybe it's the extent_buffer::start naming. For now, just add some comment. Link: https://bugzilla.kernel.org/show_bug.cgi?id=202817 [ Inspired by above report, the report itself is already addressed ] Signed-off-by: Qu Wenruo Reviewed-by: Josef Bacik --- fs/btrfs/extent_io.c | 82 ++++++++++++++++++++++++-------------------- 1 file changed, 45 insertions(+), 37 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 617ea38e6fd7..4eb35a1338c1 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5620,6 +5620,34 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num) return ret; } +static void report_eb_range(const struct extent_buffer *eb, unsigned long start, + unsigned long len) +{ + btrfs_warn(eb->fs_info, +"btrfs: bad eb rw request, eb bytenr=%llu len=%lu rw start=%lu len=%lu\n", + eb->start, eb->len, start, len); + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); +} + +/* + * Check if the [start, start + len) range is valid before reading/writing + * the eb. + * NOTE: @start and @len are offset *INSIDE* the eb, *NOT* logical address. + * + * Caller should not touch the dst/src memory if this function returns error. + */ +static inline int check_eb_range(const struct extent_buffer *eb, + unsigned long start, unsigned long len) +{ + /* start, start + len should not go beyond eb->len nor overflow */ + if (unlikely(start > eb->len || start + len > eb->len || + len > eb->len)) { + report_eb_range(eb, start, len); + return -EINVAL; + } + return 0; +} + void read_extent_buffer(const struct extent_buffer *eb, void *dstv, unsigned long start, unsigned long len) { @@ -5630,12 +5658,8 @@ void read_extent_buffer(const struct extent_buffer *eb, void *dstv, char *dst = (char *)dstv; unsigned long i = start >> PAGE_SHIFT; - 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); + if (check_eb_range(eb, start, len)) return; - } offset = offset_in_page(start); @@ -5700,8 +5724,8 @@ int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv, unsigned long i = start >> PAGE_SHIFT; int ret = 0; - WARN_ON(start > eb->len); - WARN_ON(start + len > eb->start + eb->len); + if (check_eb_range(eb, start, len)) + return -EINVAL; offset = offset_in_page(start); @@ -5754,8 +5778,8 @@ void write_extent_buffer(const struct extent_buffer *eb, const void *srcv, char *src = (char *)srcv; unsigned long i = start >> PAGE_SHIFT; - WARN_ON(start > eb->len); - WARN_ON(start + len > eb->start + eb->len); + if (check_eb_range(eb, start, len)) + return; offset = offset_in_page(start); @@ -5783,8 +5807,8 @@ void memzero_extent_buffer(const struct extent_buffer *eb, unsigned long start, char *kaddr; unsigned long i = start >> PAGE_SHIFT; - WARN_ON(start > eb->len); - WARN_ON(start + len > eb->start + eb->len); + if (check_eb_range(eb, start, len)) + return; offset = offset_in_page(start); @@ -5828,6 +5852,10 @@ void copy_extent_buffer(const struct extent_buffer *dst, char *kaddr; unsigned long i = dst_offset >> PAGE_SHIFT; + if (check_eb_range(dst, dst_offset, len) || + check_eb_range(src, src_offset, len)) + return; + WARN_ON(src->len != dst_len); offset = offset_in_page(dst_offset); @@ -6017,25 +6045,15 @@ void memcpy_extent_buffer(const struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { - struct btrfs_fs_info *fs_info = dst->fs_info; size_t cur; size_t dst_off_in_page; size_t src_off_in_page; unsigned long dst_i; unsigned long src_i; - if (src_offset + len > dst->len) { - btrfs_err(fs_info, - "memmove bogus src_offset %lu move len %lu dst len %lu", - src_offset, len, dst->len); - BUG(); - } - if (dst_offset + len > dst->len) { - btrfs_err(fs_info, - "memmove bogus dst_offset %lu move len %lu dst len %lu", - dst_offset, len, dst->len); - BUG(); - } + if (check_eb_range(dst, dst_offset, len) || + check_eb_range(dst, src_offset, len)) + return; while (len > 0) { dst_off_in_page = offset_in_page(dst_offset); @@ -6062,7 +6080,6 @@ void memmove_extent_buffer(const struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { - struct btrfs_fs_info *fs_info = dst->fs_info; size_t cur; size_t dst_off_in_page; size_t src_off_in_page; @@ -6071,18 +6088,9 @@ void memmove_extent_buffer(const struct extent_buffer *dst, unsigned long dst_i; unsigned long src_i; - if (src_offset + len > dst->len) { - btrfs_err(fs_info, - "memmove bogus src_offset %lu move len %lu len %lu", - src_offset, len, dst->len); - BUG(); - } - if (dst_offset + len > dst->len) { - btrfs_err(fs_info, - "memmove bogus dst_offset %lu move len %lu len %lu", - dst_offset, len, dst->len); - BUG(); - } + if (check_eb_range(dst, dst_offset, len) || + check_eb_range(dst, src_offset, len)) + return; if (dst_offset < src_offset) { memcpy_extent_buffer(dst, dst_offset, src_offset, len); return; -- 2.28.0