2022-02-25 11:26:16

by Jia-Ju Bai

Subject: [PATCH] md: bcache: check the return value of kzalloc() in detached_dev_do_request()

The function kzalloc() in detached_dev_do_request() can fail, so its
return value should be checked.

Fixes: bc082a55d25c (bcache: fix inaccurate io state for detached bcache devices)
Reported-by: TOTE Robot <[email protected]>
Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/md/bcache/request.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index d15aae6c51c1..1b5ccfa93b8c 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -1107,6 +1107,8 @@ static void detached_dev_do_request(struct bcache_device *d, struct bio *bio,
* which would call closure_get(&dc->disk.cl)
*/
ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO);
+ if (!ddip)
+ return;
ddip->d = d;
/* Count on the bcache device */
ddip->orig_bdev = orig_bdev;
--
2.17.1

2022-03-02 10:53:28

by Coly Li

Subject: Re: [PATCH] md: bcache: check the return value of kzalloc() in detached_dev_do_request()

On 2/25/22 4:20 PM, Jia-Ju Bai wrote:
> The function kzalloc() in detached_dev_do_request() can fail, so its
> return value should be checked.
>
> Fixes: bc082a55d25c (bcache: fix inaccurate io state for detached bcache devices)
> Reported-by: TOTE Robot <[email protected]>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/md/bcache/request.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
> index d15aae6c51c1..1b5ccfa93b8c 100644
> --- a/drivers/md/bcache/request.c
> +++ b/drivers/md/bcache/request.c
> @@ -1107,6 +1107,8 @@ static void detached_dev_do_request(struct bcache_device *d, struct bio *bio,
> * which would call closure_get(&dc->disk.cl)
> */
> ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO);

Yes this is a potential problem, may result NULL pointer deference.


> + if (!ddip)
> + return;

The fix here is incorrect. A proper way to fix might be something like this,

    if (!ddip) {

        bio->bi_status = BLK_STS_RESOURCE;

        bio->bi_end_io(bio);

        return;

    }


The orignal patch will make I/O task be in sleep forever.

> ddip->d = d;
> /* Count on the bcache device */
> ddip->orig_bdev = orig_bdev;

2022-03-03 01:45:06

by Jia-Ju Bai

Subject: Re: [PATCH] md: bcache: check the return value of kzalloc() in detached_dev_do_request()

On 2022/3/2 18:11, Coly Li wrote:
> On 2/25/22 4:20 PM, Jia-Ju Bai wrote:
>> The function kzalloc() in detached_dev_do_request() can fail, so its
>> return value should be checked.
>>
>> Fixes: bc082a55d25c (bcache: fix inaccurate io state for detached
>> bcache devices)
>> Reported-by: TOTE Robot <[email protected]>
>> Signed-off-by: Jia-Ju Bai <[email protected]>
>> ---
>>   drivers/md/bcache/request.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
>> index d15aae6c51c1..1b5ccfa93b8c 100644
>> --- a/drivers/md/bcache/request.c
>> +++ b/drivers/md/bcache/request.c
>> @@ -1107,6 +1107,8 @@ static void detached_dev_do_request(struct
>> bcache_device *d, struct bio *bio,
>>        * which would call closure_get(&dc->disk.cl)
>>        */
>>       ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO);
>
> Yes this is a potential problem, may result NULL pointer deference.
>
>
>> +    if (!ddip)
>> +        return;
>
> The fix here is incorrect. A proper way to fix might be something like
> this,
>
>     if (!ddip) {
>
>         bio->bi_status = BLK_STS_RESOURCE;
>
>         bio->bi_end_io(bio);
>
>         return;
>
>     }
>
>
> The orignal patch will make I/O task be in sleep forever.
>
>>       ddip->d = d;
>>       /* Count on the bcache device */
>>       ddip->orig_bdev = orig_bdev;
>

Hi Coly,

Thanks for the advice!
I will send a V2 patch.


Best wishes,
Jia-Ju Bai