[PATCH 6.12 143/265] ALSA: usb-audio: Use correct version for UAC3 header validation

Greg Kroah-Hartman
2026-03-12T20:20:56Z

From: Jun Seo <jun.seo.93@proton.me>

commit 54f9d645a5453d0bfece0c465d34aaf072ea99fa upstream.

The entry of the validators table for UAC3 AC header descriptor is
defined with the wrong protocol version UAC_VERSION_2, while it should
have been UAC_VERSION_3. This results in the validator never matching
for actual UAC3 devices (protocol == UAC_VERSION_3), causing their
header descriptors to bypass validation entirely. A malicious USB
device presenting a truncated UAC3 header could exploit this to cause
out-of-bounds reads when the driver later accesses unvalidated
descriptor fields.

The bug was introduced in the same commit as the recently fixed UAC3
feature unit sub-type typo, and appears to be from the same copy-paste
error when the UAC3 section was created from the UAC2 section.

Fixes: 57f8770620e9 ("ALSA: usb-audio: More validations of descriptor units")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jun Seo <jun.seo.93@proton.me>
Link: https://patch.msgid.link/20260226010820.36529-1-jun.seo.93@proton.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/usb/validate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/usb/validate.c
+++ b/sound/usb/validate.c
@@ -281,7 +281,7 @@ static const struct usb_desc_validator a
/* UAC_VERSION_2, UAC2_SAMPLE_RATE_CONVERTER: not implemented yet */

/* UAC3 */
- FIXED(UAC_VERSION_2, UAC_HEADER, struct uac3_ac_header_descriptor),
+ FIXED(UAC_VERSION_3, UAC_HEADER, struct uac3_ac_header_descriptor),
FIXED(UAC_VERSION_3, UAC_INPUT_TERMINAL,
struct uac3_input_terminal_descriptor),
FIXED(UAC_VERSION_3, UAC_OUTPUT_TERMINAL,