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        Wed, 19 Jul 2017 01:13:38 -0400
Subject: Re: 4.12 NULL pointer dereference in kmem_cache_free on USB storage
 removal
To: Bart Van Assche <Bart.VanAssche@wdc.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
References: <alpine.LRH.2.20.1707132319290.24138@math.ut.ee>
 <1499980058.2740.22.camel@wdc.com>
From: Yagmur Oymak <yagmur.oymak@gmail.com>
Message-ID: <952856d9-5f6b-98db-98e3-6348d428e894@gmail.com>
Date: Wed, 19 Jul 2017 08:13:28 +0300
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Hello,

That patch fixes the problem, as far as I tested. However, it still is
not included in stable by 4.12.2. The problem persists there, and is
fixed when this patch is applied on top of it. What to to about it?

Thanks,

Yagmur Oymak.


On 07/14/2017 12:07 AM, Bart Van Assche wrote:
> On Thu, 2017-07-13 at 23:24 +0300, Meelis Roos wrote:
>> [258062.320700] RIP: 0010:kmem_cache_free+0x12/0x160
>> [258062.320886] Call Trace:
>> [258062.320897]  scsi_exit_rq+0x4d/0x60
>> [258062.320909]  free_request_size+0x1c/0x30
>> [258062.320923]  mempool_destroy+0x1d/0x60
>> [258062.320935]  blk_exit_rl+0x1b/0x40
>> [258062.320946]  __blk_release_queue+0x7d/0x120
>> [258062.320959]  process_one_work+0x1af/0x340
>> [258062.320972]  worker_thread+0x43/0x3e0
>> [258062.320984]  kthread+0xfe/0x130
>> [258062.320995]  ? create_worker+0x170/0x170
>> [258062.321007]  ? kthread_create_on_node+0x40/0x40
>> [258062.321022]  ret_from_fork+0x22/0x30
> Hello Meelis,
>
> Thank you for your report. Can you apply commit 8e6882545d8c ("scsi: Avoid
> that scsi_exit_rq() triggers a use-after-free") on top of kernel v4.12 and
> retest? That commit has been tagged "Cc: stable" so I hope that this patch
> will be included in kernel v4.12.1. However, that kernel is not yet available
> unfortunately ...
>
> Thanks,
>
> Bart.