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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 272C4C678DB for ; Tue, 7 Mar 2023 18:53:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232483AbjCGSxo (ORCPT ); Tue, 7 Mar 2023 13:53:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229907AbjCGSx1 (ORCPT ); Tue, 7 Mar 2023 13:53:27 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CC13AB0AA for ; Tue, 7 Mar 2023 10:41:22 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C3B2C61535 for ; Tue, 7 Mar 2023 18:41:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9A82C4339B; Tue, 7 Mar 2023 18:41:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678214480; bh=LUkVtC5AYQvxaTmeuTp8hV33VpT8kS1fvNgHTpvjK90=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ShrYmOwXxEmw8yUBn6tpPUS0KhA607igjQw9qXcKmbsn8FT8WF5XFbm0aVjCnYAlj hbyH8MjfdcVIR7Ncq4F5D5pdbhKQXYouLB0Kg+ps7kBqNhiEPD65lZoQOOTmj01FIY PPTPQaKXYfXdhYqXyx4ukZxwwsns/a+4XjTj5Djs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mikulas Patocka , Sweet Tea Dorminy , Mike Snitzer Subject: [PATCH 6.1 806/885] dm flakey: dont corrupt the zero page Date: Tue, 7 Mar 2023 18:02:20 +0100 Message-Id: <20230307170036.903483113@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170001.594919529@linuxfoundation.org> References: <20230307170001.594919529@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mikulas Patocka commit f50714b57aecb6b3dc81d578e295f86d9c73f078 upstream. When we need to zero some range on a block device, the function __blkdev_issue_zero_pages submits a write bio with the bio vector pointing to the zero page. If we use dm-flakey with corrupt bio writes option, it will corrupt the content of the zero page which results in crashes of various userspace programs. Glibc assumes that memory returned by mmap is zeroed and it uses it for calloc implementation; if the newly mapped memory is not zeroed, calloc will return non-zeroed memory. Fix this bug by testing if the page is equal to ZERO_PAGE(0) and avoiding the corruption in this case. Cc: stable@vger.kernel.org Fixes: a00f5276e266 ("dm flakey: Properly corrupt multi-page bios.") Signed-off-by: Mikulas Patocka Reviewed-by: Sweet Tea Dorminy Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-flakey.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/md/dm-flakey.c +++ b/drivers/md/dm-flakey.c @@ -303,8 +303,11 @@ static void corrupt_bio_data(struct bio */ bio_for_each_segment(bvec, bio, iter) { if (bio_iter_len(bio, iter) > corrupt_bio_byte) { - char *segment = (page_address(bio_iter_page(bio, iter)) - + bio_iter_offset(bio, iter)); + char *segment; + struct page *page = bio_iter_page(bio, iter); + if (unlikely(page == ZERO_PAGE(0))) + break; + segment = (page_address(page) + bio_iter_offset(bio, iter)); segment[corrupt_bio_byte] = fc->corrupt_bio_value; DMDEBUG("Corrupting data bio=%p by writing %u to byte %u " "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",