Re: [PATCH 1/2] block/backup: avoid integer overflow of `max-workers`

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

10/5/21 19:11, Stefano Garzarella wrote:
> QAPI generates `struct BackupPerf` where `max-workers` value is stored
> in an `int64_t` variable.
> But block_copy_async(), and the underlying code, uses an `int` parameter.
> 
> At the end that variable is used to initialize `max_busy_tasks` in
> block/aio_task.c causing the following assertion failure if a value
> greater than INT_MAX(2147483647) is used:
> 
>    ../block/aio_task.c:63: aio_task_pool_wait_one: Assertion `pool->busy_tasks > 0' failed.
> 
> Let's check that `max-workers` doesn't exceed INT_MAX and print an
> error in that case.
> 
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2009310

I glad to see that someone experiments with my experimental API :)

> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

> ---
>   block/backup.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/block/backup.c b/block/backup.c
> index 687d2882bc..8b072db5d9 100644
> --- a/block/backup.c
> +++ b/block/backup.c
> @@ -407,8 +407,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
>           return NULL;
>       }
>   
> -    if (perf->max_workers < 1) {
> -        error_setg(errp, "max-workers must be greater than zero");
> +    if (perf->max_workers < 1 || perf->max_workers > INT_MAX) {
> +        error_setg(errp, "max-workers must be between 1 and %d", INT_MAX);
>           return NULL;
>       }
>   
> 


-- 
Best regards,
Vladimir