ALSA: line6: Clear prev_fbuf on capture buffer release

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Summary

CVECVE-2026-99271
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-07 14:17:02 UTC
Updated2026-11-07 14:17:02 UTC
DescriptionIn 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().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 862d9268f40a6e10cef24eb226e738fb69ce8aa7 git Not specified
CNA Linux Linux affected 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 22c82f33ff0b68d37041adf1dea5533a5863cd31 git Not specified
CNA Linux Linux affected 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 aa118c8f61d59387961d58ffae831c5259a9f222 git Not specified
CNA Linux Linux affected 4.0 Not specified
CNA Linux Linux unaffected 4.0 semver Not specified
CNA Linux Linux unaffected 6.18.61 6.18.* semver Not specified
CNA Linux Linux unaffected 7.3.2 7.3.* semver Not specified
CNA Linux Linux unaffected 7.4-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/aa118c8f61d59387961d58ffae831c5259a9f222 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/862d9268f40a6e10cef24eb226e738fb69ce8aa7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/22c82f33ff0b68d37041adf1dea5533a5863cd31 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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