From: Jens Axboe <axboe@kernel.dk>
To: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Tejun Heo <tj@kernel.org>, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH] blkcg: Fix use-after-free of q->root_blkg and q->root_rl.blkg
Date: Mon, 22 Oct 2012 20:43:50 +0200 [thread overview]
Message-ID: <508593E6.2060303@kernel.dk> (raw)
In-Reply-To: <507E7030.9070607@ce.jp.nec.com>
On 2012-10-17 10:45, Jun'ichi Nomura wrote:
> 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.
Thanks, applied to for-linus (and marked stable).
--
Jens Axboe
next prev parent reply other threads:[~2012-10-22 18:43 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 5:11 [PATCH] Fix use-after-free of q->root_blkg and q->root_rl.blkg Jun'ichi Nomura
2012-10-10 15:59 ` Vivek Goyal
2012-10-11 1:31 ` Jun'ichi Nomura
2012-10-11 18:55 ` Vivek Goyal
2012-10-16 23:20 ` Tejun Heo
2012-10-17 0:02 ` Jun'ichi Nomura
2012-10-17 8:45 ` [PATCH] blkcg: " Jun'ichi Nomura
2012-10-18 21:21 ` Tejun Heo
2012-10-22 18:43 ` Jens Axboe [this message]
2012-10-17 13:47 ` [PATCH] " Vivek Goyal
2012-10-18 2:56 ` Jun'ichi Nomura
2012-10-18 13:31 ` Vivek Goyal
2012-10-18 21:20 ` Tejun Heo
2012-10-19 14:53 ` Vivek Goyal
2012-10-22 0:55 ` Jun'ichi Nomura
2012-10-22 1:15 ` [PATCH] blkcg: stop iteration early if root_rl is the only request list Jun'ichi Nomura
2012-10-22 15:31 ` Vivek Goyal
2012-10-22 18:43 ` Jens Axboe
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