Re: paride/pf.c: blk-mq use-after-free (kernel v5.0)

From: Jens Axboe
Date: Fri Mar 15 2019 - 12:33:22 EST


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