Re: [PATCH 09/31] block: Avoid that blk_exit_rl() triggers a use-after-free

Tejun Heo
2017-05-24T15:09:35Z

On Tue, May 23, 2017 at 05:33:58PM -0700, Bart Van Assche wrote:
> Since the introduction of the .init_rq_fn() and .exit_rq_fn() it
> is essential that the memory allocated for struct request_queue
> stays around until all blk_exit_rl() calls have finished. Hence
> make blk_init_rl() take a reference on struct request_queue.
>
> This patch fixes the following crash:
>
> general protection fault: 0000 [#2] SMP
> CPU: 3 PID: 28 Comm: ksoftirqd/3 Tainted: G D 4.12.0-rc2-dbg+ #2
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
> task: ffff88013a108040 task.stack: ffffc9000071c000
> RIP: 0010:free_request_size+0x1a/0x30
> RSP: 0018:ffffc9000071fd38 EFLAGS: 00010202
> RAX: 6b6b6b6b6b6b6b6b RBX: ffff880067362a88 RCX: 0000000000000003
> RDX: ffff880067464178 RSI: ffff880067362a88 RDI: ffff880135ea4418
> RBP: ffffc9000071fd40 R08: 0000000000000000 R09: 0000000100180009
> R10: ffffc9000071fd38 R11: ffffffff81110800 R12: ffff88006752d3d8
> R13: ffff88006752d3d8 R14: ffff88013a108040 R15: 000000000000000a
> FS: 0000000000000000(0000) GS:ffff88013fd80000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fa8ec1edb00 CR3: 0000000138ee8000 CR4: 00000000001406e0
> Call Trace:
> mempool_destroy.part.10+0x21/0x40
> mempool_destroy+0xe/0x10
> blk_exit_rl+0x12/0x20
> blkg_free+0x4d/0xa0
> __blkg_release_rcu+0x59/0x170
> rcu_process_callbacks+0x260/0x4e0
> __do_softirq+0x116/0x250
> smpboot_thread_fn+0x123/0x1e0
> kthread+0x109/0x140
> ret_from_fork+0x31/0x40
>
> Fixes: commit e9c787e65c0c ("scsi: allocate scsi_cmnd structures as part of struct request")
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Cc: Jens Axboe <axboe@fb.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: <stable@vger.kernel.org> # v4.11+

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

--
tejun