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Tue, 16 Jun 2020 14:17:43 +0100 From: Mark Hills To: Takashi Iwai Subject: [PATCH 2/3] echoaudio: Prevent races in calls to set_audio_format() Date: Tue, 16 Jun 2020 14:17:42 +0100 Message-Id: <20200616131743.4793-2-mark@xwax.org> X-Mailer: git-send-email 2.17.5 In-Reply-To: <2006161409060.30751@stax.localdomain> References: <2006161409060.30751@stax.localdomain> Cc: alsa-devel@alsa-project.org X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" The function uses chip->comm_page which needs locking against other use at the same time. Signed-off-by: Mark Hills --- sound/pci/echoaudio/echoaudio.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c index 82a49dfd2384..8cf08988959f 100644 --- a/sound/pci/echoaudio/echoaudio.c +++ b/sound/pci/echoaudio/echoaudio.c @@ -711,9 +711,22 @@ static int pcm_prepare(struct snd_pcm_substream *substream) if (snd_BUG_ON(pipe_index >= px_num(chip))) return -EINVAL; - if (snd_BUG_ON(!is_pipe_allocated(chip, pipe_index))) + + /* + * We passed checks we can do independently; now take + * exclusive control + */ + + spin_lock(&chip->lock); + + if (snd_BUG_ON(!is_pipe_allocated(chip, pipe_index))) { + spin_unlock(&chip->lock); return -EINVAL; + } + set_audio_format(chip, pipe_index, &format); + spin_unlock(&chip->lock); + return 0; }