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65635cbc37
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Jun'ichi Nomura 65635cbc37 blkcg: Fix use-after-free of q->root_blkg and q->root_rl.blkg 
blk_put_rl() does not call blkg_put() for q->root_rl because we
don't take request list reference on q->root_blkg.
However, if root_blkg is once attached then detached (freed),
blk_put_rl() is confused by the bogus pointer in q->root_blkg.

For example, with !CONFIG_BLK_DEV_THROTTLING &&
CONFIG_CFQ_GROUP_IOSCHED,
switching IO scheduler from cfq to deadline will cause system stall
after the following warning with 3.6:

> WARNING: at /work/build/linux/block/blk-cgroup.h:250
> blk_put_rl+0x4d/0x95()
> Modules linked in: bridge stp llc sunrpc acpi_cpufreq freq_table mperf
> ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4
> Pid: 0, comm: swapper/0 Not tainted 3.6.0 #1
> Call Trace:
>  <IRQ>  [<ffffffff810453bd>] warn_slowpath_common+0x85/0x9d
>  [<ffffffff810453ef>] warn_slowpath_null+0x1a/0x1c
>  [<ffffffff811d5f8d>] blk_put_rl+0x4d/0x95
>  [<ffffffff811d614a>] __blk_put_request+0xc3/0xcb
>  [<ffffffff811d71a3>] blk_finish_request+0x232/0x23f
>  [<ffffffff811d76c3>] ? blk_end_bidi_request+0x34/0x5d
>  [<ffffffff811d76d1>] blk_end_bidi_request+0x42/0x5d
>  [<ffffffff811d7728>] blk_end_request+0x10/0x12
>  [<ffffffff812cdf16>] scsi_io_completion+0x207/0x4d5
>  [<ffffffff812c6fcf>] scsi_finish_command+0xfa/0x103
>  [<ffffffff812ce2f8>] scsi_softirq_done+0xff/0x108
>  [<ffffffff811dcea5>] blk_done_softirq+0x8d/0xa1
>  [<ffffffff810915d5>] ?
>  generic_smp_call_function_single_interrupt+0x9f/0xd7
>  [<ffffffff8104cf5b>] __do_softirq+0x102/0x213
>  [<ffffffff8108a5ec>] ? lock_release_holdtime+0xb6/0xbb
>  [<ffffffff8104d2b4>] ? raise_softirq_irqoff+0x9/0x3d
>  [<ffffffff81424dfc>] call_softirq+0x1c/0x30
>  [<ffffffff81011beb>] do_softirq+0x4b/0xa3
>  [<ffffffff8104cdb0>] irq_exit+0x53/0xd5
>  [<ffffffff8102d865>] smp_call_function_single_interrupt+0x34/0x36
>  [<ffffffff8142486f>] call_function_single_interrupt+0x6f/0x80
>  <EOI>  [<ffffffff8101800b>] ? mwait_idle+0x94/0xcd
>  [<ffffffff81018002>] ? mwait_idle+0x8b/0xcd
>  [<ffffffff81017811>] cpu_idle+0xbb/0x114
>  [<ffffffff81401fbd>] rest_init+0xc1/0xc8
>  [<ffffffff81401efc>] ? csum_partial_copy_generic+0x16c/0x16c
>  [<ffffffff81cdbd3d>] start_kernel+0x3d4/0x3e1
>  [<ffffffff81cdb79e>] ? kernel_init+0x1f7/0x1f7
>  [<ffffffff81cdb2dd>] x86_64_start_reservations+0xb8/0xbd
>  [<ffffffff81cdb3e3>] x86_64_start_kernel+0x101/0x110

This patch clears q->root_blkg and q->root_rl.blkg when root blkg
is destroyed.

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-10-22 22:00:26 +02:00
..
partitions s390/partitions: make partition detection independent from DASD ioctls 2012-09-26 15:45:05 +02:00
blk-cgroup.c blkcg: Fix use-after-free of q->root_blkg and q->root_rl.blkg 2012-10-22 22:00:26 +02:00
blk-cgroup.h blkcg: implement per-blkg request allocation 2012-06-26 18:42:49 -04:00
blk-core.c Merge branch 'for-3.7/core' of git://git.kernel.dk/linux-block 2012-10-11 09:04:23 +09:00
blk-exec.c [SCSI] block: Fix blk_execute_rq_nowait() dead queue handling 2012-07-20 08:58:39 +01:00
blk-flush.c blk-flush: move the queue kick into 2011-10-24 16:24:31 +02:00
blk-integrity.c block: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:31:12 -04:00
blk-ioc.c block: uninitialized ioc->nr_tasks triggers WARN_ON 2012-08-01 12:17:27 +02:00
blk-iopoll.c tree-wide: fix assorted typos all over the place 2009-12-04 15:39:55 +01:00
blk-lib.c block: Make blkdev_issue_zeroout use WRITE SAME 2012-09-20 14:31:49 +02:00
blk-map.c block: re-use existing 'reading' variable instead of checking direction again 2011-12-21 15:27:24 +01:00
blk-merge.c block: Implement support for WRITE SAME 2012-09-20 14:31:45 +02:00
blk-settings.c block: Implement support for WRITE SAME 2012-09-20 14:31:45 +02:00
blk-softirq.c sched, block: Unify cache detection 2012-01-27 13:28:48 +01:00
blk-sysfs.c block: lift the initial queue bypass mode on blk_register_queue() instead of blk_init_allocated_queue() 2012-09-21 15:32:57 +02:00
blk-tag.c block/blk-tag.c: Remove useless kfree 2012-09-12 22:25:12 +02:00
blk-throttle.c workqueue: use mod_delayed_work() instead of __cancel + queue 2012-08-21 13:18:24 -07:00
blk-timeout.c block: Drop dead function blk_abort_queue() 2012-06-15 08:46:23 +02:00
blk.h block: Clean up special command handling logic 2012-09-20 14:31:38 +02:00
bsg-lib.c block: drop custom queue draining used by scsi_transport_{iscsi|fc} 2012-06-25 11:53:48 +02:00
bsg.c bsg: fix sysfs link remove warning 2012-02-08 20:02:03 +01:00
cfq-iosched.c block: blkcg_policy_cfq shouldn't be used if !CONFIG_CFQ_GROUP_IOSCHED 2012-06-04 10:02:29 +02:00
compat_ioctl.c block: Add BLKROTATIONAL ioctl 2012-01-11 16:29:31 +01:00
deadline-iosched.c elevator: make elevator_init_fn() return 0/-errno 2012-03-06 21:27:21 +01:00
elevator.c block: Clean up special command handling logic 2012-09-20 14:31:38 +02:00
genhd.c Merge branch 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2012-10-02 09:54:49 -07:00
ioctl.c Merge branch 'for-3.7/core' of git://git.kernel.dk/linux-block 2012-10-11 09:04:23 +09:00
Kconfig move fs/partitions to block/ 2012-01-03 22:54:06 -05:00
Kconfig.iosched blkcg: make CONFIG_BLK_CGROUP bool 2012-03-06 21:27:21 +01:00
Makefile separate partition format handling from generic code 2012-01-03 22:54:06 -05:00
noop-iosched.c elevator: make elevator_init_fn() return 0/-errno 2012-03-06 21:27:21 +01:00
partition-generic.c block: add partition resize function to blkpg ioctl 2012-08-01 12:24:18 +02:00
scsi_ioctl.c scsi: Silence unnecessary warnings about ioctl to partition 2012-06-15 12:52:46 +02:00