High · published December 9, 2025
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.