published October 18, 2026
In the Linux kernel, the following vulnerability has been resolved:
ALSA: ua101: reject mismatched capture/playback packet sizes
detect_usb_format() cross-checks bSubframeSize, bBitResolution and
tSamFreq between the capture and playback interfaces, but never relates
the two endpoints' wMaxPacketSize and bNrChannels. Each playback URB
gets a buffer of ua->playback.max_packet_bytes, while the number of
bytes written into it is derived from the capture stream:
capture_urb_complete() computes frames from the received capture packet
and capture.frame_bytes, and start_usb_playback() and playback_work()
multiply that by playback.frame_bytes.
A device declaring a large capture wMaxPacketSize with few capture
channels and a small playback wMaxPacketSize with many playback channels
therefore memset()s and memcpy()s past the end of the playback buffer,
in open() of the PCM node the driver registers during probe.
usb_submit_urb() rejects the over-long iso_frame_desc[0].length with
-EMSGSIZE, but only after the write.
Reject such descriptors at probe time. Genuine UA-101/UA-1000 hardware
declares proportional packet sizes and is unaffected.
BUG: KASAN: slab-out-of-bounds in start_usb_playback (sound/usb/misc/ua101.c:586)
Write of size 2048 at addr ffff8881098f3c00 by task exploit/5021
Call Trace:
__asan_memset (mm/kasan/shadow.c:84)
start_usb_playback (sound/usb/misc/ua101.c:586)
playback_pcm_open (sound/usb/misc/ua101.c:679)
snd_pcm_open_substream (sound/core/pcm_native.c:2829)
snd_pcm_open (sound/core/pcm_native.c:2865 sound/core/pcm_native.c:2932)
snd_pcm_playback_open (sound/core/pcm_native.c:2891)
snd_open (sound/core/sound.c:166)
chrdev_open (fs/char_dev.c:411)
do_dentry_open (fs/open.c:996)
vfs_open (fs/open.c:1101)
path_openat (fs/namei.c:4837 fs/namei.c:5000)
do_file_open (fs/namei.c:5029)
do_sys_openat2 (fs/open.c:1417)
__x64_sys_openat (fs/open.c:1423 fs/open.c:1439 fs/open.c:1434)
do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
The buggy address belongs to the object at ffff8881098f3c00
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 0 bytes inside of
allocated 168-byte region [ffff8881098f3c00, ffff8881098f3ca8)