Bug 2420336 (CVE-2023-53866)

Summary: CVE-2023-53866 kernel: ASoC: soc-compress: Reposition and add pcm_mutex
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: low    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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Doc Text:
A locking issue was found in the ASoC (ALSA SoC) compressed audio subsystem in the Linux kernel. When DPCM (Dynamic PCM) compressed streams are started, several functions access resources without properly holding the card->pcm_mutex lock. This triggers lock assertion warnings and can cause kernel panics if panic_on_warn is enabled.
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Description OSIDB Bzimport 2025-12-09 02:03:50 UTC
In the Linux kernel, the following vulnerability has been resolved:

ASoC: soc-compress: Reposition and add pcm_mutex

If panic_on_warn is set and compress stream(DPCM) is started,
then kernel panic occurred because card->pcm_mutex isn't held appropriately.
In the following functions, warning were issued at this line
"snd_soc_dpcm_mutex_assert_held".

static int dpcm_be_connect(struct snd_soc_pcm_runtime *fe,
		struct snd_soc_pcm_runtime *be, int stream)
{
	...
	snd_soc_dpcm_mutex_assert_held(fe);
	...
}

void dpcm_be_disconnect(struct snd_soc_pcm_runtime *fe, int stream)
{
	...
	snd_soc_dpcm_mutex_assert_held(fe);
	...
}

void snd_soc_runtime_action(struct snd_soc_pcm_runtime *rtd,
			    int stream, int action)
{
	...
	snd_soc_dpcm_mutex_assert_held(rtd);
	...
}

int dpcm_dapm_stream_event(struct snd_soc_pcm_runtime *fe, int dir,
	int event)
{
	...
	snd_soc_dpcm_mutex_assert_held(fe);
	...
}

These functions are called by soc_compr_set_params_fe, soc_compr_open_fe
and soc_compr_free_fe
without pcm_mutex locking. And this is call stack.

[  414.527841][ T2179] pc : dpcm_process_paths+0x5a4/0x750
[  414.527848][ T2179] lr : dpcm_process_paths+0x37c/0x750
[  414.527945][ T2179] Call trace:
[  414.527949][ T2179]  dpcm_process_paths+0x5a4/0x750
[  414.527955][ T2179]  soc_compr_open_fe+0xb0/0x2cc
[  414.527972][ T2179]  snd_compr_open+0x180/0x248
[  414.527981][ T2179]  snd_open+0x15c/0x194
[  414.528003][ T2179]  chrdev_open+0x1b0/0x220
[  414.528023][ T2179]  do_dentry_open+0x30c/0x594
[  414.528045][ T2179]  vfs_open+0x34/0x44
[  414.528053][ T2179]  path_openat+0x914/0xb08
[  414.528062][ T2179]  do_filp_open+0xc0/0x170
[  414.528068][ T2179]  do_sys_openat2+0x94/0x18c
[  414.528076][ T2179]  __arm64_sys_openat+0x78/0xa4
[  414.528084][ T2179]  invoke_syscall+0x48/0x10c
[  414.528094][ T2179]  el0_svc_common+0xbc/0x104
[  414.528099][ T2179]  do_el0_svc+0x34/0xd8
[  414.528103][ T2179]  el0_svc+0x34/0xc4
[  414.528125][ T2179]  el0t_64_sync_handler+0x8c/0xfc
[  414.528133][ T2179]  el0t_64_sync+0x1a0/0x1a4
[  414.528142][ T2179] Kernel panic - not syncing: panic_on_warn set ...

So, I reposition and add pcm_mutex to resolve lockdep error.