From 8053f21675b073b379cbca258ee4a3f3850dfa94 Mon Sep 17 00:00:00 2001 From: Nicolin Chen Date: Tue, 26 Jul 2016 14:55:51 -0700 Subject: [PATCH] ASoC: dapm: Add a dummy snd_pcm_runtime to avoid NULL pointer access The SND_SOC_DAPM_PRE_PMU case would call startup()/hw_params() that might access substream->runtime through other functions. For example: Unable to handle kernel NULL pointer dereference at virtual address [....] PC is at snd_pcm_hw_rule_add+0x24/0x1b0 LR is at snd_pcm_hw_constraint_list+0x20/0x28 [....] Process arecord (pid: 424, stack limit = 0xffffffc1ecaf0020) Call trace: [] snd_pcm_hw_rule_add+0x24/0x1b0 [] snd_pcm_hw_constraint_list+0x20/0x28 [] cs53l30_pcm_startup+0x24/0x30 [] snd_soc_dai_link_event+0x290/0x354 [] dapm_seq_check_event.isra.31+0x134/0x2c8 [] dapm_seq_run_coalesced+0x94/0x1c8 [] dapm_seq_run+0xa4/0x404 [] dapm_power_widgets+0x524/0x984 [] snd_soc_dapm_stream_event+0x8c/0xa8 [] soc_pcm_prepare+0x10c/0x1ec [] snd_pcm_do_prepare+0x1c/0x38 [] snd_pcm_action_single+0x40/0x88 [] snd_pcm_action_nonatomic+0x70/0x90 [] snd_pcm_common_ioctl1+0xb6c/0xdd8 [] snd_pcm_capture_ioctl1+0x200/0x334 [] snd_pcm_ioctl_compat+0x648/0x95c [] compat_SyS_ioctl+0xac/0xfc4 [] el0_svc_naked+0x24/0x28 ---[ end trace 0dc4f99c2759c35c ]--- So this patch adds a dummy runtime for the original dummy substream to merely avoid the NULL pointer access. Signed-off-by: Nicolin Chen Signed-off-by: Mark Brown --- sound/soc/soc-dapm.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index 8698c26773b3..d908ff8f9755 100644 --- a/sound/soc/soc-dapm.c +++ b/sound/soc/soc-dapm.c @@ -3493,6 +3493,7 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w, const struct snd_soc_pcm_stream *config = w->params + w->params_select; struct snd_pcm_substream substream; struct snd_pcm_hw_params *params = NULL; + struct snd_pcm_runtime *runtime = NULL; u64 fmt; int ret; @@ -3541,6 +3542,14 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w, memset(&substream, 0, sizeof(substream)); + /* Allocate a dummy snd_pcm_runtime for startup() and other ops() */ + runtime = kzalloc(sizeof(*runtime), GFP_KERNEL); + if (!runtime) { + ret = -ENOMEM; + goto out; + } + substream.runtime = runtime; + switch (event) { case SND_SOC_DAPM_PRE_PMU: substream.stream = SNDRV_PCM_STREAM_CAPTURE; @@ -3606,6 +3615,7 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w, } out: + kfree(runtime); kfree(params); return ret; }