Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
ASoC: soc-core: flush delayed work before removing DAIs and widgets
When a sound card is unbound while a PCM stream is open, a use-after-free can occur in snd_soc_dapm_stream_event(), called from the close_delayed_work workqueue handler.
During unbind, snd_soc_unbind_card() flushes delayed work and then calls soc_cleanup_card_resources(). Inside cleanup, snd_card_disconnect_sync() releases all PCM file descriptors, and the resulting PCM close path can call snd_soc_dapm_stream_stop() which schedules new delayed work with a pmdown_time timer delay. Since this happens after the flush in snd_soc_unbind_card(), the new work is not caught. soc_remove_link_components() then frees DAPM widgets before this work fires, leading to the use-after-free.
The existing flush in soc_free_pcm_runtime() also cannot help as it runs after soc_remove_link_components() has already freed the widgets.
Add a flush in soc_cleanup_card_resources() after snd_card_disconnect_sync() (after which no new PCM closes can schedule further delayed work) and before soc_remove_link_dais() and soc_remove_link_components() (which tear down the structures the delayed work accesses).
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 20.04 ELS
- Affected packages:
- kernel-uek @ 5.4.17 (+8 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| AlmaLinux 9.2 ESU | Planned | — |
| AlmaLinux 9.6 ESU | Planned | — |
| Debian 11 | Released |
37 kernels
|
| Debian 11 cloud | Released |
17 kernels
|
| Debian 13 | Planned | — |
| Ubuntu 22.04 | Planned | — |
| Ubuntu 24.04 | Planned | — |