From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1546708-1519218909-2-11729501942910315472 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1519218908; b=okWlQPPO5gFq08bVykzP6Dqr83bn05XiD5EU2df2VFdLgOB bEbD2R9ZNDEZaY43HmwPoaCblbJDnmDjh3s0Y9AVkFbojFF96i5wv1Xx4xpijTXJ iO8/u1S7fH7lABTDpURsVhMvO0efE38neGcKrsMWr5z/NACdJr2lsoxU0pA0wJHz m2U5Ns8hwQdDiFFm2PRJ85uN657RhZLRa379VZ+tPMjcf1MmCWD3lW6er72o3iAK 7XFQrsjQj6UcGYNAGIaLedqHqsccaE3hbSBSjc++Q8Dpa68kkpp5AjqznIr9274K alL10g/ngqE8AGfhwm/BeXGGXdTzMhEJCN69bAg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1519218908; bh=hadewxZHm/0fGiSNmT3kTEWm9B 9N2OMB8dxu7i8Srf8=; b=Ys5djejiRZ7svBz629iC95bw85AghB2+zNgeD1EDTh QHKhhGCMr9m9uRr07x2fMU1tHg+NixFtXXHC+VS8b6mLNQZMv9vQ2GHG05jFviJR zFHSzlQOI/RkcnTG7/FxZ8blFcaV+3pPoyCrPlzkf/6Hw91e7NKsl62Le3Q4UGXZ i9adKe5UhAnAQb73uMb4LP+kstOrx8pqb/iS8XCWdBqycPnlXWbI9GZs1fX9x5fY LYv9LGYDCln+71Nf4LSbR1i9eZcuNTx/k1RME5GyWZbe7+yAkV0ACCso+S0Ao4XD c4beVsWWTfAhTL7HFkcCmSjZzu73o+3Z57qT8trRXS+A== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965707AbeBUNNT (ORCPT ); Wed, 21 Feb 2018 08:13:19 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:46002 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753216AbeBUNNQ (ORCPT ); Wed, 21 Feb 2018 08:13:16 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , Mike Snitzer Subject: [PATCH 4.15 134/163] dm: correctly handle chained bios in dec_pending() Date: Wed, 21 Feb 2018 13:49:23 +0100 Message-Id: <20180221124537.599868211@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180221124529.931834518@linuxfoundation.org> References: <20180221124529.931834518@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit 8dd601fa8317243be887458c49f6c29c2f3d719f upstream. dec_pending() is given an error status (possibly 0) to be recorded against a bio. It can be called several times on the one 'struct dm_io', and it is careful to only assign a non-zero error to io->status. However when it then assigned io->status to bio->bi_status, it is not careful and could overwrite a genuine error status with 0. This can happen when chained bios are in use. If a bio is chained beneath the bio that this dm_io is handling, the child bio might complete and set bio->bi_status before the dm_io completes. This has been possible since chained bios were introduced in 3.14, and has become a lot easier to trigger with commit 18a25da84354 ("dm: ensure bio submission follows a depth-first tree walk") as that commit caused dm to start using chained bios itself. A particular failure mode is that if a bio spans an 'error' target and a working target, the 'error' fragment will complete instantly and set the ->bi_status, and the other fragment will normally complete a little later, and will clear ->bi_status. The fix is simply to only assign io_error to bio->bi_status when io_error is not zero. Reported-and-tested-by: Milan Broz Cc: stable@vger.kernel.org (v3.14+) Signed-off-by: NeilBrown Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -817,7 +817,8 @@ static void dec_pending(struct dm_io *io queue_io(md, bio); } else { /* done with normal IO or empty flush */ - bio->bi_status = io_error; + if (io_error) + bio->bi_status = io_error; bio_endio(bio); } }