From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out5-smtp.messagingengine.com ([66.111.4.29]:42371 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750736AbbFCFiv (ORCPT ); Wed, 3 Jun 2015 01:38:51 -0400 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id A15BB20609 for ; Wed, 3 Jun 2015 01:38:50 -0400 (EDT) Subject: FAILED: patch "[PATCH] dm: fix NULL pointer when clone_and_map_rq returns" failed to apply to 4.0-stable tree To: j-nomura@ce.jp.nec.com, bart.vanassche@sandisk.com, snitzer@redhat.com Cc: From: Date: Wed, 03 Jun 2015 14:38:47 +0900 Message-ID: <1433309927168114@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: The patch below does not apply to the 4.0-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >>From 3a1407559a593d4360af12dd2df5296bf8eb0d28 Mon Sep 17 00:00:00 2001 From: Junichi Nomura Date: Wed, 27 May 2015 04:22:07 +0000 Subject: [PATCH] dm: fix NULL pointer when clone_and_map_rq returns !DM_MAPIO_REMAPPED When stacking request-based DM on blk_mq device, request cloning and remapping are done in a single call to target's clone_and_map_rq(). The clone is allocated and valid only if clone_and_map_rq() returns DM_MAPIO_REMAPPED. The "IS_ERR(clone)" check in map_request() does not cover all the !DM_MAPIO_REMAPPED cases that are possible (E.g. if underlying devices are not ready or unavailable, clone_and_map_rq() may return DM_MAPIO_REQUEUE without ever having established an ERR_PTR). Fix this by explicitly checking for a return that is not DM_MAPIO_REMAPPED in map_request(). Without this fix, DM core may call setup_clone() for a NULL clone and oops like this: BUG: unable to handle kernel NULL pointer dereference at 0000000000000068 IP: [] blk_rq_prep_clone+0x7d/0x137 ... CPU: 2 PID: 5793 Comm: kdmwork-253:3 Not tainted 4.0.0-nm #1 ... Call Trace: [] map_tio_request+0xa9/0x258 [dm_mod] [] kthread_worker_fn+0xfd/0x150 [] ? kthread_parkme+0x24/0x24 [] ? kthread_parkme+0x24/0x24 [] kthread+0xe6/0xee [] ? put_lock_stats+0xe/0x20 [] ? __init_kthread_worker+0x5b/0x5b [] ret_from_fork+0x58/0x90 [] ? __init_kthread_worker+0x5b/0x5b Fixes: e5863d9ad ("dm: allocate requests in target when stacking on blk-mq devices") Reported-by: Bart Van Assche Signed-off-by: Jun'ichi Nomura Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # 4.0+ diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 0bf79a0bad37..1c62ed8d09f4 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1972,8 +1972,8 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq, dm_kill_unmapped_request(rq, r); return r; } - if (IS_ERR(clone)) - return DM_MAPIO_REQUEUE; + if (r != DM_MAPIO_REMAPPED) + return r; if (setup_clone(clone, rq, tio, GFP_ATOMIC)) { /* -ENOMEM */ ti->type->release_clone_rq(clone);