[alsa-devel] [PATCH 2/2] Fix a stack buffer overflow bug in check_input_term

[Salvatore Bonaccorso]

Hi Hui,

On Fri, Aug 30, 2019 at 05:47:29PM -0400, Hui Peng wrote:
> `check_input_term` recursively calls itself with input from
> device side (e.g., uac_input_terminal_descriptor.bCSourceID)
> as argument (id). In `check_input_term`, if `check_input_term`
> is called with the same `id` argument as the caller, it triggers
> endless recursive call, resulting kernel space stack overflow.
> 
> This patch fixes the bug by adding a bitmap to `struct mixer_build`
> to keep track of the checked ids and stop the execution if some id
> has been checked (similar to how parse_audio_unit handles unitid
> argument).
> 
> CVE: CVE-2018-15118

Similar to the previous one, this should be CVE-2019-15118 as far I
can tell.

Regards,
Salvatore