ALSA: usb: 6fire: Avoid embedded URBs

The USB 6fire driver uses URBs embedded in different structs for PCM,
MIDI and communication, and this is basically a buggy implementation
nowadays; since a URB is managed with a refcount, this may lead to a
UAF when the URB is released asynchronously.

For addressing the problem, this patch converts those embedded URBs to
ones that are properly allocated via usb_alloc_urb().  The
pcm_urb.packets[] is gone, as it's allocated by usb_alloc_urb(), hence
it's found in urb.iso_frame_desc[] instead.

The conversions are rather straightforward; each embedded struct urb
is changed to a pointer, and its callers are updated accordingly.
The resource for those structs are released in the common destructor
functions (usb6fire_comm_free(), etc), which are called at both the
init error path and the disconnect.

No functional changes, only compile-tested.

Link: https://lore.kernel.org/20260903130757.0668310a.michal.pecio@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260903160458.1938392-4-tiwai@suse.de
This commit is contained in:
Takashi Iwai 2026-09-03 18:04:39 +02:00
commit 9fe49dbc02
6 changed files with 136 additions and 86 deletions