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Ming Lei 7acba7c062 blk-mq: fix race between timeout and freeing request 
commit 0048b4837a upstream.

Inside timeout handler, blk_mq_tag_to_rq() is called
to retrieve the request from one tag. This way is obviously
wrong because the request can be freed any time and some
fiedds of the request can't be trusted, then kernel oops
might be triggered[1].

Currently wrt. blk_mq_tag_to_rq(), the only special case is
that the flush request can share same tag with the request
cloned from, and the two requests can't be active at the same
time, so this patch fixes the above issue by updating tags->rqs[tag]
with the active request(either flush rq or the request cloned
from) of the tag.

Also blk_mq_tag_to_rq() gets much simplified with this patch.

Given blk_mq_tag_to_rq() is mainly for drivers and the caller must
make sure the request can't be freed, so in bt_for_each() this
helper is replaced with tags->rqs[tag].

[1] kernel oops log
[  439.696220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000158^M
[  439.697162] IP: [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
[  439.700653] PGD 7ef765067 PUD 7ef764067 PMD 0 ^M
[  439.700653] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M
[  439.700653] Dumping ftrace buffer:^M
[  439.700653]    (ftrace buffer empty)^M
[  439.700653] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M
[  439.700653] CPU: 6 PID: 2779 Comm: stress-ng-sigfd Not tainted 4.2.0-rc5-next-20150805+ #265^M
[  439.730500] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M
[  439.730500] task: ffff880605308000 ti: ffff88060530c000 task.ti: ffff88060530c000^M
[  439.730500] RIP: 0010:[<ffffffff812d89ba>]  [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
[  439.730500] RSP: 0018:ffff880819203da0  EFLAGS: 00010283^M
[  439.730500] RAX: ffff880811b0e000 RBX: ffff8800bb465f00 RCX: 0000000000000002^M
[  439.730500] RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000^M
[  439.730500] RBP: ffff880819203db0 R08: 0000000000000002 R09: 0000000000000000^M
[  439.730500] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000202^M
[  439.730500] R13: ffff880814104800 R14: 0000000000000002 R15: ffff880811a2ea00^M
[  439.730500] FS:  00007f165b3f5740(0000) GS:ffff880819200000(0000) knlGS:0000000000000000^M
[  439.730500] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M
[  439.730500] CR2: 0000000000000158 CR3: 00000007ef766000 CR4: 00000000000006e0^M
[  439.730500] Stack:^M
[  439.730500]  0000000000000008 ffff8808114eed90 ffff880819203e00 ffffffff812dc104^M
[  439.755663]  ffff880819203e40 ffffffff812d9f5e 0000020000000000 ffff8808114eed80^M
[  439.755663] Call Trace:^M
[  439.755663]  <IRQ> ^M
[  439.755663]  [<ffffffff812dc104>] bt_for_each+0x6e/0xc8^M
[  439.755663]  [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M
[  439.755663]  [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M
[  439.755663]  [<ffffffff812dc1b3>] blk_mq_tag_busy_iter+0x55/0x5e^M
[  439.755663]  [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M
[  439.755663]  [<ffffffff812d8911>] blk_mq_rq_timer+0x5d/0xd4^M
[  439.755663]  [<ffffffff810a3e10>] call_timer_fn+0xf7/0x284^M
[  439.755663]  [<ffffffff810a3d1e>] ? call_timer_fn+0x5/0x284^M
[  439.755663]  [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M
[  439.755663]  [<ffffffff810a46d6>] run_timer_softirq+0x1ce/0x1f8^M
[  439.755663]  [<ffffffff8104c367>] __do_softirq+0x181/0x3a4^M
[  439.755663]  [<ffffffff8104c76e>] irq_exit+0x40/0x94^M
[  439.755663]  [<ffffffff81031482>] smp_apic_timer_interrupt+0x33/0x3e^M
[  439.755663]  [<ffffffff815559a4>] apic_timer_interrupt+0x84/0x90^M
[  439.755663]  <EOI> ^M
[  439.755663]  [<ffffffff81554350>] ? _raw_spin_unlock_irq+0x32/0x4a^M
[  439.755663]  [<ffffffff8106a98b>] finish_task_switch+0xe0/0x163^M
[  439.755663]  [<ffffffff8106a94d>] ? finish_task_switch+0xa2/0x163^M
[  439.755663]  [<ffffffff81550066>] __schedule+0x469/0x6cd^M
[  439.755663]  [<ffffffff8155039b>] schedule+0x82/0x9a^M
[  439.789267]  [<ffffffff8119b28b>] signalfd_read+0x186/0x49a^M
[  439.790911]  [<ffffffff8106d86a>] ? wake_up_q+0x47/0x47^M
[  439.790911]  [<ffffffff811618c2>] __vfs_read+0x28/0x9f^M
[  439.790911]  [<ffffffff8117a289>] ? __fget_light+0x4d/0x74^M
[  439.790911]  [<ffffffff811620a7>] vfs_read+0x7a/0xc6^M
[  439.790911]  [<ffffffff8116292b>] SyS_read+0x49/0x7f^M
[  439.790911]  [<ffffffff81554c17>] entry_SYSCALL_64_fastpath+0x12/0x6f^M
[  439.790911] Code: 48 89 e5 e8 a9 b8 e7 ff 5d c3 0f 1f 44 00 00 55 89
f2 48 89 e5 41 54 41 89 f4 53 48 8b 47 60 48 8b 1c d0 48 8b 7b 30 48 8b
53 38 <48> 8b 87 58 01 00 00 48 85 c0 75 09 48 8b 97 88 0c 00 00 eb 10
^M
[  439.790911] RIP  [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
[  439.790911]  RSP <ffff880819203da0>^M
[  439.790911] CR2: 0000000000000158^M
[  439.790911] ---[ end trace d40af58949325661 ]---^M

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
[bwh: Backported to 3.16:
 - Flush state is in struct request_queue, not struct blk_flush_queue
 - Flush request cloning is done in blk_mq_clone_flush_request() rather
   than blk_kick_flush()
 - Drop changes in bt{,_tags}_for_each()
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
History 2018-03-03 15:52:29 +00:00
..
partitions mac: validate mac_partition is within sector 2015-12-18 16:06:30 +00:00
bio-integrity.c bio integrity: do not assume bio_integrity_pool exists if bioset exists 2015-08-10 09:54:14 +01:00
bio.c more bio_map_user_iov() leak fixes 2018-01-01 20:51:50 +00:00
blk-cgroup.c blkcg: fix gendisk reference leak in blkg_conf_prep() 2015-08-11 09:57:43 +01:00
blk-cgroup.h blkcg: Annotate blkg_hint correctly 2017-02-23 03:54:03 +00:00
blk-core.c blktrace: Fix potential deadlock between delete & sysfs ops 2018-02-13 18:42:21 +00:00
blk-exec.c block: blk-exec.c: Cleaning up local variable address returnd 2014-06-08 19:51:31 -06:00
blk-flush.c blk-mq: fix race between timeout and freeing request 2018-03-03 15:52:29 +00:00
blk-integrity.c bio-integrity: Convert to bvec_iter 2013-11-23 22:33:50 -08:00
blk-ioc.c block: Substitute rcu_access_pointer() for rcu_dereference_raw() 2014-02-18 12:21:26 -08:00
blk-iopoll.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next 2014-06-03 12:57:53 -07:00
blk-lib.c block/blk-lib.c: make __blkdev_issue_zeroout static 2014-05-26 17:39:09 -06:00
blk-map.c block: remove struct request buffer member 2014-04-15 14:03:02 -06:00
blk-merge.c Fix bug in blk_rq_merge_ok 2015-04-10 10:03:59 +01:00
blk-mq-cpu.c blk-mq: add file comments and update copyright notices 2014-05-28 10:15:41 -06:00
blk-mq-cpumap.c blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map 2015-01-12 15:43:57 +00:00
blk-mq-sysfs.c blk-mq: fix buffer overflow when reading sysfs file of 'pending' 2015-09-28 10:21:41 +01:00
blk-mq-tag.c sbitmap: fix wakeup hang after sbq resize 2017-06-05 21:16:55 +01:00
blk-mq-tag.h blk-mq: fix race between timeout and freeing request 2018-03-03 15:52:29 +00:00
blk-mq.c blk-mq: fix race between timeout and freeing request 2018-03-03 15:52:29 +00:00
blk-mq.h blk-mq: fix schedule from atomic context 2014-06-03 21:04:39 -06:00
blk-settings.c block: fix alignment_offset math that assumes io_min is a power-of-2 2014-11-17 14:11:44 +00:00
blk-softirq.c block: fix regression with block enabled tagging 2014-04-09 21:54:06 -06:00
blk-sysfs.c blk-mq: Fix a use-after-free 2015-01-15 10:43:41 +00:00
blk-tag.c block: don't assume last put of shared tags is for the host 2014-07-08 12:25:28 +02:00
blk-throttle.c blk-throttle: check stats_cpu before reading it from sysfs 2015-03-02 15:04:36 +00:00
blk-timeout.c block: ensure that the timer is always added 2014-05-30 15:41:39 -06:00
blk.h block: remove elv_abort_queue and blk_abort_flushes 2014-06-11 15:31:21 -06:00
bounce.c mm: convert some level-less printks to pr_* 2014-06-06 16:08:18 -07:00
bsg-lib.c bsg: Remove unused function bsg_goose_queue() 2012-12-06 14:33:02 +01:00
bsg.c sg_write()/bsg_write() is not fit to be called under KERNEL_DS 2017-02-23 03:54:47 +00:00
cfq-iosched.c cfq-iosched: handle failure of cfq group allocation 2015-03-02 13:17:10 +00:00
cmdline-parser.c block: remove unrelated header files and export symbol 2014-01-21 20:18:26 -08:00
compat_ioctl.c block: provide compat ioctl for BLKZEROOUT 2014-07-14 12:27:20 +02:00
deadline-iosched.c block: Stop abusing csd.list for fifo_time 2014-02-24 14:46:32 -08:00
elevator.c Revert "block: add __init to elv_register" 2014-06-22 16:34:11 -06:00
genhd.c block: fix bdi vs gendisk lifetime mismatch 2016-11-20 01:17:05 +00:00
ioctl.c block: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO 2013-11-08 09:05:31 -07:00
ioprio.c block: fix use-after-free in sys_ioprio_get() 2016-08-22 22:38:26 +01:00
Kconfig block: change config option name for cmdline partition parsing 2013-09-30 14:31:02 -07:00
Kconfig.iosched blkcg: make CONFIG_BLK_CGROUP bool 2012-03-06 21:27:21 +01:00
Makefile block: move mm/bounce.c to block/ 2014-05-19 20:01:52 -06:00
noop-iosched.c elevator: Fix a race in elevator switching 2013-07-03 13:25:24 +02:00
partition-generic.c block: fix an error code in add_partition() 2017-09-15 18:29:49 +01:00
scsi_ioctl.c scsi: Fix error handling in SCSI_IOCTL_SEND_COMMAND 2014-11-13 11:48:39 +00:00