From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1524142-1518326439-2-10690129278369727450 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='US', FromHeader='uk', 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=1518326439; b=l+UuIep/JHT6iZFQMsbPsBLW+KtXIzkJLQD0eOpw8aXfFvt q/WYxwKiN18tqX7TVrrlStKO1SqZP5ia1f3mnuFLG9DG6yFdjyjflblgO2AXv1Uy aoof8ijKzz0UBYCg8ZyouSDQWfP/AM4oGxrQ/LkwSgg75CZKxglqvdGuNlpjQ44I mBAnBrucCn6Ytulj0zlBdrlmqkeWpXqlfTwlK46dRuT+d9Rsb7e5U91ZfI+ppLuN IoFs9Fjnu9CE60Xxl9p9psOWlAXYhWMAO5kZZVXJbLynmGcMT2LOs10l6pStjKnB 16HjPbjcRPBmRIRX/X1Y+wYXUudD07PlgIui0tA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:content-transfer-encoding :mime-version:from:to:cc:date:message-id:subject:in-reply-to :sender:list-id; s=arctest; t=1518326439; bh=tBghGxHgO/i6P4OMwPk VTs53PQ1rm+yUR/Ga7T3w91s=; b=iQz/Bxr5uTXf6PezdI4Fu/I4NxctrOr9R8O NQ4ECKtK1cHx1CWdgu/0YT02RgBNpLm3aiXoh6HJhn6kcGFFjAhf6/HJQsghlLPD Xrrs9sptzzTZSRaa+Ffwjx13yZViSkautzRNyJx50gzfGdBFuZLsqIfLiNr8tc6r Tlcxy/SSoKHY8T6ix90PapMCDMuxz+pSt6qTECw6HjsQAbnOE6C0sapsvAzdYfdm zLeuFQEBYXxsEcQSIHpYnWlHp1O+4syP1Tm5xNwxgVHyzFDq1pJeH15nwi8ZCa3o Ust00dO0qYy3ARfoUdEyr7tRzvpBrHdJSy7HHn64bNVfliI8xSw== ARC-Authentication-Results: i=1; mx4.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; 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=decadent.org.uk header.result=pass header_is_org_domain=yes Authentication-Results: mx4.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; 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=decadent.org.uk header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932191AbeBKFSO (ORCPT ); Sun, 11 Feb 2018 00:18:14 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42726 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932162AbeBKFSM (ORCPT ); Sun, 11 Feb 2018 00:18:12 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jens Axboe" , "Michael Lyle" , "Kent Overstreet" , "Jorg Bornschein" , "Coly Li" Date: Sun, 11 Feb 2018 04:31:11 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 022/136] bcache: check ca->alloc_thread initialized before wake up it In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false 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: 3.16.54-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Coly Li commit 91af8300d9c1d7c6b6a2fd754109e08d4798b8d8 upstream. In bcache code, sysfs entries are created before all resources get allocated, e.g. allocation thread of a cache set. There is posibility for NULL pointer deference if a resource is accessed but which is not initialized yet. Indeed Jorg Bornschein catches one on cache set allocation thread and gets a kernel oops. The reason for this bug is, when bch_bucket_alloc() is called during cache set registration and attaching, ca->alloc_thread is not properly allocated and initialized yet, call wake_up_process() on ca->alloc_thread triggers NULL pointer deference failure. A simple and fast fix is, before waking up ca->alloc_thread, checking whether it is allocated, and only wake up ca->alloc_thread when it is not NULL. Signed-off-by: Coly Li Reported-by: Jorg Bornschein Cc: Kent Overstreet Reviewed-by: Michael Lyle Signed-off-by: Jens Axboe Signed-off-by: Ben Hutchings --- drivers/md/bcache/alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -406,7 +406,8 @@ long bch_bucket_alloc(struct cache *ca, finish_wait(&ca->set->bucket_wait, &w); out: - wake_up_process(ca->alloc_thread); + if (ca->alloc_thread) + wake_up_process(ca->alloc_thread); trace_bcache_alloc(ca, reserve);