The recently introduced USB-audio descriptor validator had a stupid
copy&paste error that may lead to an unexpected overlook of too short
descriptors for processing and extension units. It's likely the cause
of the report triggered by syzkaller fuzzer. Let's fix it.
Fixes: 57f8770620 ("ALSA: usb-audio: More validations of descriptor units")
Reported-by: syzbot+0620f79a1978b1133fd7@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/s5hsgnkdbsl.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Introduce a new helper to validate each audio descriptor unit before
and check the unit before actually accessing it. This should harden
against the OOB access cases with malformed descriptors that have been
recently frequently reported by fuzzers.
The existing descriptor checks are still kept although they become
superfluous after this patch. They'll be cleaned up eventually
later.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Iwai