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Thu, 7 Mar 2019 07:46:00 +0800 From: KaiChieh Chuang To: Subject: [PATCH] ASoC: dpcm: prevent snd_soc_dpcm use after free Date: Thu, 7 Mar 2019 07:45:59 +0800 Message-ID: <1551915959-27150-1-git-send-email-kaichieh.chuang@mediatek.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190306_154620_300123_C3C57660 X-CRM114-Status: GOOD ( 11.85 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, kuninori.morimoto.gx@renesas.com, hochi.huang@mediatek.com, perex@perex.cz, linux-mediatek@lists.infradead.org, michael.hsiao@mediatek.com, kaichieh.chuang@mediatek.com Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP the dpcm get from fe_clients/be_clients may be free before use possible race condition between void dpcm_be_disconnect( ... list_del(&dpcm->list_be); list_del(&dpcm->list_fe); kfree(dpcm); ... and for_each_dpcm_fe() for_each_dpcm_be*() race condition example Thread 1: snd_soc_dapm_mixer_update_power() -> soc_dpcm_runtime_update() -> dpcm_be_disconnect() -> kfree(dpcm); Thread 2: dpcm_fe_dai_trigger() -> dpcm_be_dai_trigger() -> snd_soc_dpcm_can_be_free_stop() -> if (dpcm->fe == fe) Excpetion Scenario: two FE link to same BE FE1 -> BE FE2 -> Thread 1: switch of mixer between FE2 -> BE Thread 2: pcm_stop FE1 Add a spin lock at snd_soc_card level, to protect the dpcm instance. The lock may be used in atomic context, so use spin lock. Exception: Unable to handle kernel paging request at virtual address dead0000000000e0 pc=<> [] dpcm_be_dai_trigger+0x29c/0x47c sound/soc/soc-pcm.c:3226 if (dpcm->fe == fe) lr=<> [] dpcm_fe_dai_do_trigger+0x94/0x26c Backtrace: [] notify_die+0x68/0xb8 [] die+0x118/0x2a8 [] __do_kernel_fault+0x13c/0x14c [] do_translation_fault+0x64/0xa0 [] do_mem_abort+0x4c/0xd0 [] el1_da+0x24/0x40 [] dpcm_be_dai_trigger+0x29c/0x47c [] dpcm_fe_dai_do_trigger+0x94/0x26c [] dpcm_fe_dai_trigger+0x3c/0x44 [] snd_pcm_do_stop+0x50/0x5c [] snd_pcm_action+0xb4/0x13c [] snd_pcm_drop+0xa0/0x128 [] snd_pcm_common_ioctl+0x9d8/0x30f0 [] snd_pcm_ioctl_compat+0x29c/0x2f14 [] compat_SyS_ioctl+0x128/0x244 [] el0_svc_naked+0x34/0x38 [] 0xffffffffffffffff Signed-off-by: KaiChieh Chuang --- include/sound/soc.h | 2 ++ sound/soc/soc-core.c | 1 + sound/soc/soc-pcm.c | 33 ++++++++++++++++++++++++++------- 3 files changed, 29 insertions(+), 7 deletions(-) diff --git a/include/sound/soc.h b/include/sound/soc.h index eb7db60..1e2be35 100644 --- a/include/sound/soc.h +++ b/include/sound/soc.h @@ -1083,6 +1083,8 @@ struct snd_soc_card { struct mutex mutex; struct mutex dapm_mutex; + spinlock_t dpcm_lock; + bool instantiated; bool topology_shortname_created; diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c index 5a5764d..d887576 100644 --- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c @@ -2820,6 +2820,7 @@ int snd_soc_register_card(struct snd_soc_card *card) card->instantiated = 0; mutex_init(&card->mutex); mutex_init(&card->dapm_mutex); + spin_lock_init(&card->dpcm_lock); return snd_soc_bind_card(card); } diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c index a5b40e8..9020a06 100644 --- a/sound/soc/soc-pcm.c +++ b/sound/soc/soc-pcm.c @@ -1228,8 +1228,10 @@ static int dpcm_be_connect(struct snd_soc_pcm_runtime *fe, dpcm->fe = fe; be->dpcm[stream].runtime = fe->dpcm[stream].runtime; dpcm->state = SND_SOC_DPCM_LINK_STATE_NEW; + spin_lock(&fe->card->dpcm_lock); list_add(&dpcm->list_be, &fe->dpcm[stream].be_clients); list_add(&dpcm->list_fe, &be->dpcm[stream].fe_clients); + spin_unlock(&fe->card->dpcm_lock); dev_dbg(fe->dev, "connected new DPCM %s path %s %s %s\n", stream ? "capture" : "playback", fe->dai_link->name, @@ -1294,8 +1296,10 @@ void dpcm_be_disconnect(struct snd_soc_pcm_runtime *fe, int stream) #ifdef CONFIG_DEBUG_FS debugfs_remove(dpcm->debugfs_state); #endif + spin_lock(&fe->card->dpcm_lock); list_del(&dpcm->list_be); list_del(&dpcm->list_fe); + spin_unlock(&fe->card->dpcm_lock); kfree(dpcm); } } @@ -1548,9 +1552,11 @@ void dpcm_clear_pending_state(struct snd_soc_pcm_runtime *fe, int stream) { struct snd_soc_dpcm *dpcm; + spin_lock(&fe->card->dpcm_lock); for_each_dpcm_be(fe, stream, dpcm) dpcm->be->dpcm[stream].runtime_update = SND_SOC_DPCM_UPDATE_NO; + spin_unlock(&fe->card->dpcm_lock); } static void dpcm_be_dai_startup_unwind(struct snd_soc_pcm_runtime *fe, @@ -2640,11 +2646,13 @@ static int dpcm_run_update_startup(struct snd_soc_pcm_runtime *fe, int stream) dpcm_be_dai_shutdown(fe, stream); disconnect: /* disconnect any non started BEs */ + spin_lock(&fe->card->dpcm_lock); for_each_dpcm_be(fe, stream, dpcm) { struct snd_soc_pcm_runtime *be = dpcm->be; if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START) dpcm->state = SND_SOC_DPCM_LINK_STATE_FREE; } + spin_unlock(&fe->card->dpcm_lock); return ret; } @@ -3220,7 +3228,9 @@ int snd_soc_dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe, { struct snd_soc_dpcm *dpcm; int state; + int ret = 1; + spin_lock(&fe->card->dpcm_lock); for_each_dpcm_fe(be, stream, dpcm) { if (dpcm->fe == fe) @@ -3229,12 +3239,15 @@ int snd_soc_dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe, state = dpcm->fe->dpcm[stream].state; if (state == SND_SOC_DPCM_STATE_START || state == SND_SOC_DPCM_STATE_PAUSED || - state == SND_SOC_DPCM_STATE_SUSPEND) - return 0; + state == SND_SOC_DPCM_STATE_SUSPEND) { + ret = 0; + break; + } } + spin_unlock(&fe->card->dpcm_lock); /* it's safe to free/stop this BE DAI */ - return 1; + return ret; } EXPORT_SYMBOL_GPL(snd_soc_dpcm_can_be_free_stop); @@ -3247,7 +3260,9 @@ int snd_soc_dpcm_can_be_params(struct snd_soc_pcm_runtime *fe, { struct snd_soc_dpcm *dpcm; int state; + int ret = 1; + spin_lock(&fe->card->dpcm_lock); for_each_dpcm_fe(be, stream, dpcm) { if (dpcm->fe == fe) @@ -3257,12 +3272,15 @@ int snd_soc_dpcm_can_be_params(struct snd_soc_pcm_runtime *fe, if (state == SND_SOC_DPCM_STATE_START || state == SND_SOC_DPCM_STATE_PAUSED || state == SND_SOC_DPCM_STATE_SUSPEND || - state == SND_SOC_DPCM_STATE_PREPARE) - return 0; + state == SND_SOC_DPCM_STATE_PREPARE) { + ret = 0; + break; + } } + spin_unlock(&fe->card->dpcm_lock); /* it's safe to change hw_params */ - return 1; + return ret; } EXPORT_SYMBOL_GPL(snd_soc_dpcm_can_be_params); @@ -3328,6 +3346,7 @@ static ssize_t dpcm_show_state(struct snd_soc_pcm_runtime *fe, goto out; } + spin_lock(&fe->card->dpcm_lock); for_each_dpcm_be(fe, stream, dpcm) { struct snd_soc_pcm_runtime *be = dpcm->be; params = &dpcm->hw_params; @@ -3348,7 +3367,7 @@ static ssize_t dpcm_show_state(struct snd_soc_pcm_runtime *fe, params_channels(params), params_rate(params)); } - + spin_unlock(&fe->card->dpcm_lock); out: return offset; }