CVE-2026-99271
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().
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74; < 862d9268f40a6e10cef24eb226e738fb69ce8aa7 (affected, git) ≥ 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74; < 22c82f33ff0b68d37041adf1dea5533a5863cd31 (affected, git) ≥ 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74; < aa118c8f61d59387961d58ffae831c5259a9f222 (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
4.0 (affected) ≥ 0; < 4.0 (unaffected, semver) ≥ 6.18.61; ≤ 6.18.* (unaffected, semver) ≥ 7.3.2; ≤ 7.3.* (unaffected, semver) ≥ 7.4-rc1; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
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