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Subject: Re: paride/pf.c: blk-mq use-after-free (kernel v5.0)
To:     Randy Dunlap <rdunlap@infradead.org>,
        linux-block <linux-block@vger.kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, Tim Waugh <tim@cyberelk.net>,
        linux-parport@lists.infradead.org
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 <59cb035e-6880-de5a-33c5-d4db6ed910f4@kernel.dk>
 <4a2adc33-ef38-6a5f-65ee-8fcfaa0948a9@infradead.org>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <d22bf156-06df-ec67-121d-7dce65088b1a@kernel.dk>
Date:   Fri, 15 Mar 2019 10:33:16 -0600
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On 3/14/19 5:49 PM, Randy Dunlap wrote:
> On 3/14/19 4:43 PM, Jens Axboe wrote:
>> On 3/13/19 5:09 PM, Randy Dunlap wrote:
>>> On 3/11/19 6:34 PM, Randy Dunlap wrote:
>>>> On 3/11/19 6:25 PM, Randy Dunlap wrote:
>>>>> [Has this already been addressed/fixed?]>>
>>>>
>>>> Same bug occurs with paride/pcd.c driver.
>>>
>>> This still happens (in blk-mq) in v5.0-11053-gebc551f2b8f9 of Mar. 12, 2019,
>>> around 4pm PT.  [caused by paride: pf.c and pcd.c)
>>
>> I'll take a look at this, been busy with other stuff. How are you
>> reproducing this? I'm assuming you don't actually have any hardware :-)
> 
> Right.  I just load the module (pf or pcd), unload it, and
> then load it again.

Does this work?


diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c
index 96670eefaeb2..4681ddef5666 100644
--- a/drivers/block/paride/pcd.c
+++ b/drivers/block/paride/pcd.c
@@ -749,8 +749,11 @@ static int pcd_detect(void)
 		return 0;
 
 	printk("%s: No CD-ROM drive found\n", name);
-	for (unit = 0, cd = pcd; unit < PCD_UNITS; unit++, cd++)
+	for (unit = 0, cd = pcd; unit < PCD_UNITS; unit++, cd++) {
+		blk_cleanup_queue(cd->disk->queue);
+		blk_mq_free_tag_set(&cd->tag_set);
 		put_disk(cd->disk);
+	}
 	pi_unregister_driver(par_drv);
 	return -1;
 }
diff --git a/drivers/block/paride/pf.c b/drivers/block/paride/pf.c
index e92e7a8eeeb2..d27f375bb55a 100644
--- a/drivers/block/paride/pf.c
+++ b/drivers/block/paride/pf.c
@@ -761,8 +761,11 @@ static int pf_detect(void)
 		return 0;
 
 	printk("%s: No ATAPI disk detected\n", name);
-	for (pf = units, unit = 0; unit < PF_UNITS; pf++, unit++)
+	for (pf = units, unit = 0; unit < PF_UNITS; pf++, unit++) {
+		blk_cleanup_queue(pf->disk->queue);
+		blk_mq_free_tag_set(&pf->tag_set);
 		put_disk(pf->disk);
+	}
 	pi_unregister_driver(par_drv);
 	return -1;
 }

-- 
Jens Axboe