Re: [PATCH v2] ALSA: usb-audio: us144mkii: Fix null-deref in tascam_midi_in_urb_complete()

[Takashi Iwai <tiwai@suse.de>]

On Tue, 19 Aug 2025 20:51:33 +0200,
Šerif Rami wrote:
> 
> Changes in v2:
>  - Removed duplicate call to usb_put_urb() on submission failure.
>  - Removed extra blank line after the function.
>  
> The smatch tool reported a potential null pointer dereference in
> tascam_midi_in_urb_complete(). The 'tascam' variable, derived from
> 'urb->context', was checked for nullity in one place, but dereferenced
> without a check in several other places.
> 
> This patch fixes the issue by adding a null check at the beginning of
> the function. If 'tascam' is null, the function now safely exits.
> This prevents any potential crashes from null pointer dereferences.
> 
> It also fixes a latent bug where 'usb_put_urb()' could
> be called twice for the same URB on submission failure, which would
> lead to a use-after-free error.
> 
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/r/202508192109.lcMrINK1-lkp@intel.com/
> Signed-off-by: Šerif Rami <ramiserifpersia@gmail.com>

Applied now.  Thanks.


Takashi