{"id":"CVE-2026-99271","title":"ALSA: line6: Clear prev_fbuf on capture buffer release","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: line6: Clear prev_fbuf on capture buffer release\n\nA KASAN slab-use-after-free read was reported in submit_audio_out_urb()\nwhen generating an impulse test signal:\n…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 < 862d9268f40a6e10cef24eb226e738fb69ce8aa7","Linux >= 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 < 22c82f33ff0b68d37041adf1dea5533a5863cd31","Linux >= 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 < aa118c8f61d59387961d58ffae831c5259a9f222","Linux 4.0"],"published":"2026-11-07","updated":"2026-11-07","sourceUpdated":"2026-11-07T14:08:45.047Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99271","references":[{"url":"https://git.kernel.org/stable/c/862d9268f40a6e10cef24eb226e738fb69ce8aa7"},{"url":"https://git.kernel.org/stable/c/22c82f33ff0b68d37041adf1dea5533a5863cd31"},{"url":"https://git.kernel.org/stable/c/aa118c8f61d59387961d58ffae831c5259a9f222"}],"tags":["cve.org"],"ingestedAt":"2026-11-07T14:18:21.464Z","slug":"CVE-2026-99271","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nALSA: line6: Clear prev_fbuf on capture buffer release\n\nA KASAN slab-use-after-free read was reported in submit_audio_out_urb()\nwhen generating an impulse test signal:\n\n  BUG: KASAN: slab-use-after-free in create_impulse_test_signal sound/usb/line6/playback.c:76 [inline]\n  BUG: KASAN: slab-use-after-free in submit_audio_out_urb+0x1848/0x1b20 sound/usb/line6/playback.c:249\n  Read of size 2 at addr ffff888008d74870 by task syz.2.3214/7785\n\n  Allocated by task 11:\n   kmem_cache_alloc_noprof+0x2f0/0x390 mm/slub.c:4144\n   line6_buffer_acquire+0x1a1/0x220 sound/usb/line6/pcm.c:158\n   line6_pcm_acquire+0xb6/0x230 sound/usb/line6/pcm.c:329\n   line6_startup_work+0x3c/0x50 sound/usb/line6/driver.c:728\n\n  Freed by task 7785:\n   kfree+0xf8/0x390 mm/slub.c:6566\n   line6_buffer_release sound/usb/line6/pcm.c:176 [inline]\n   line6_buffer_release+0xa5/0xf0 sound/usb/line6/pcm.c:170\n   __line6_pcm_release sound/usb/line6/pcm.c:305 [inline]\n   line6_pcm_release+0x5a/0x80 sound/usb/line6/pcm.c:313\n   snd_toneport_monitor_put+0x11b/0x190 sound/usb/line6/toneport.c:183\n\nline6pcm->prev_fbuf points into the capture PCM stream buffer\n(line6pcm->in.buffer), which is updated during audio_in_callback() to\nfeed rate synchronization, software monitoring, and impulse test signal\ngeneration on playback side.\n\nWhen all capture streams are closed, line6_buffer_release() frees\npstr->buffer with kfree().  However, it does not clear line6pcm->prev_fbuf.\nIf playback is subsequently started (e.g. via impulse test signal\nvolume control snd_line6_impulse_volume_put()), submit_audio_out_urb()\ndereferences the stale pointer line6pcm->prev_fbuf under in.lock,\nresulting in a slab-use-after-free read.\n\nClear prev_fbuf and prev_fsize in line6_buffer_release() when releasing\nthe capture stream buffer under in.lock, ensuring that no stale buffer\npointer can be accessed by submit_audio_out_urb().\n\n## Affected\n\n- `Linux >= 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 < 862d9268f40a6e10cef24eb226e738fb69ce8aa7`\n- `Linux >= 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 < 22c82f33ff0b68d37041adf1dea5533a5863cd31`\n- `Linux >= 63e20df1e5b2ef8d871ecbdb6c038d554ed1ca74 < aa118c8f61d59387961d58ffae831c5259a9f222`\n- `Linux 4.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}