CVE-2026-99271 is a vulnerability in Linux Kernel
Published on November 7, 2026
ALSA: line6: Clear prev_fbuf on capture buffer release
In the Linux kernel, the following vulnerability has been resolved:
ALSA: line6: Clear prev_fbuf on capture buffer release
A KASAN slab-use-after-free read was reported in submit_audio_out_urb()
when generating an impulse test signal:
BUG: KASAN: slab-use-after-free in create_impulse_test_signal sound/usb/line6/playback.c:76 [inline]
BUG: KASAN: slab-use-after-free in submit_audio_out_urb+0x1848/0x1b20 sound/usb/line6/playback.c:249
Read of size 2 at addr ffff888008d74870 by task syz.2.3214/7785
Allocated by task 11:
kmem_cache_alloc_noprof+0x2f0/0x390 mm/slub.c:4144
line6_buffer_acquire+0x1a1/0x220 sound/usb/line6/pcm.c:158
line6_pcm_acquire+0xb6/0x230 sound/usb/line6/pcm.c:329
line6_startup_work+0x3c/0x50 sound/usb/line6/driver.c:728
Freed by task 7785:
kfree+0xf8/0x390 mm/slub.c:6566
line6_buffer_release sound/usb/line6/pcm.c:176 [inline]
line6_buffer_release+0xa5/0xf0 sound/usb/line6/pcm.c:170
__line6_pcm_release sound/usb/line6/pcm.c:305 [inline]
line6_pcm_release+0x5a/0x80 sound/usb/line6/pcm.c:313
snd_toneport_monitor_put+0x11b/0x190 sound/usb/line6/toneport.c:183
line6pcm->prev_fbuf points into the capture PCM stream buffer
(line6pcm->in.buffer), which is updated during audio_in_callback() to
feed rate synchronization, software monitoring, and impulse test signal
generation on playback side.
When all capture streams are closed, line6_buffer_release() frees
pstr->buffer with kfree(). However, it does not clear line6pcm->prev_fbuf.
If playback is subsequently started (e.g. via impulse test signal
volume control snd_line6_impulse_volume_put()), submit_audio_out_urb()
dereferences the stale pointer line6pcm->prev_fbuf under in.lock,
resulting in a slab-use-after-free read.
Clear prev_fbuf and prev_fsize in line6_buffer_release() when releasing
the capture stream buffer under in.lock, ensuring that no stale buffer
pointer can be accessed by submit_audio_out_urb().
Products Associated with CVE-2026-99271
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Affected Versions
Linux:- Version 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 and below 862d9268f40a6e10cef24eb226e738fb69ce8aa7 is affected.
- Version 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 and below 22c82f33ff0b68d37041adf1dea5533a5863cd31 is affected.
- Version 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 and below aa118c8f61d59387961d58ffae831c5259a9f222 is affected.
- Version 4.0 is affected.
- Before 4.0 is unaffected.
- Version 6.18.61, <= 6.18.* is unaffected.
- Version 7.3.2, <= 7.3.* is unaffected.
- Version 7.4-rc1, <= * is unaffected.