CVE-2024-26654: ALSA: sh: aica: reorder cleanup operations to avoid UAF bugs

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-04-01 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: sh: aica: reorder cleanup operations to avoid UAF bugs The dreamcastcard->timer could schedule the spu_dma_work and the spu_dma_work could also arm the dreamcastcard->timer. When the snd_pcm_substream is closing, the aica_channel will be deallocated. But it could still be dereferenced in the worker thread. The reason is that del_timer() will return directly regardless of whether the timer handler is running or not and the worker could be rescheduled in the timer handler. As a result, the UAF bug will happen. The racy situation is shown below: (Thread 1) | (Thread 2) snd_aicapcm_pcm_close() | ... | run_spu_dma() //worker | mod_timer() flush_work() | del_timer() | aica_period_elapsed() //timer kfree(dreamcastcard->channel) | schedule_work() | run_spu_dma() //worker ... | dreamcastcard->channel-> //USE In order to mitigate this bug and other possible corner cases, call mod_timer() conditionally in run_spu_dma(), then implement PCM sync_stop op to cancel both the timer and worker. The sync_stop op will be called from PCM core appropriately when needed.

Affected products

Debian Linux: 10.0
Linux kernel: from 2.6.23 before 4.19.312; from 4.20 before 5.4.274; from 5.5 before 5.10.215; from 5.11 before 5.15.154; from 5.16 before 6.1.84; from 6.2 before 6.6.24 — fixed in 4.19.312, 5.10.215, 5.15.154, 5.4.274, 6.1.84, 6.6.24

How to fix

Upgrade to a fixed version: Linux kernel 4.19.312, 5.10.215, 5.15.154, 5.4.274. Check the vendor advisory for mitigations.

References

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