[Devel] [PATCH 2/5] sysfs/blk-sysfs: fix uninitialized var usage

[Konstantin Khorenko]

Please, file a bug to RedHat, add me to CC there and send a notification here.

Thank you.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team

On 01/18/2016 01:27 PM, Dmitry Safonov wrote:
> One may write some shit to unpriv_sgio file (introduced by
> import RHEL7 kernel-3.10.0-229.7.2.el7), which will result in corectness
> check by function queue_var_store returning -EINVAL. Since return value
> of this function is not checked in queue_store_unpriv_sgio, function may
> result in random QUEUE_FLAG_UNPRIV_SGIO flag value.
> Since it's all done under CAP_SYS_ADMIN, it's not too critical.
>
> Found by warning:
> block/blk-sysfs.c: In function ‘queue_store_unpriv_sgio’:
> block/blk-sysfs.c:211:5: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>    if (val)
>
> Signed-off-by: Dmitry Safonov <dsafonov at odin.com>
> ---
>   block/blk-sysfs.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 21bc0c7..c08d91c 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -207,6 +207,9 @@ queue_store_unpriv_sgio(struct request_queue *q, const char *page, size_t count)
>   		return -EPERM;
>
>   	ret = queue_var_store(&val, page, count);
> +	if (ret < 0)
> +		return ret;
> +
>   	spin_lock_irq(q->queue_lock);
>   	if (val)
>   		queue_flag_set(QUEUE_FLAG_UNPRIV_SGIO, q);
>