Commit 11cb881b authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: pcm: oss: Fix a few more UBSAN fixes 



There are a few places that call round{up|down}_pow_of_two() with the
value zero, and this causes undefined behavior warnings.  Avoid
calling those macros if such a nonsense value is passed; it's a minor
optimization as well, as we handle it as either an error or a value to
be skipped, instead.

Reported-by: default avatar <syzbot+33ef0b6639a8d2d42b4c@syzkaller.appspotmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201218161730.26596-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 618de0f4

sound/core/oss/pcm_oss.c

+14 −8
Original line number Diff line number Diff line
@@ -693,6 +693,8 @@ static int snd_pcm_oss_period_size(struct snd_pcm_substream *substream, 


	oss_buffer_size = snd_pcm_plug_client_size(substream,

						   snd_pcm_hw_param_value_max(slave_params, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, NULL)) * oss_frame_size;

	if (!oss_buffer_size)

		return -EINVAL;

	oss_buffer_size = rounddown_pow_of_two(oss_buffer_size);

	if (atomic_read(&substream->mmap_count)) {

		if (oss_buffer_size > runtime->oss.mmap_bytes)
@@ -728,17 +730,21 @@ static int snd_pcm_oss_period_size(struct snd_pcm_substream *substream, 


	min_period_size = snd_pcm_plug_client_size(substream,

						   snd_pcm_hw_param_value_min(slave_params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, NULL));

	if (min_period_size) {

		min_period_size *= oss_frame_size;

		min_period_size = roundup_pow_of_two(min_period_size);

		if (oss_period_size < min_period_size)

			oss_period_size = min_period_size;

	}



	max_period_size = snd_pcm_plug_client_size(substream,

						   snd_pcm_hw_param_value_max(slave_params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, NULL));

	if (max_period_size) {

		max_period_size *= oss_frame_size;

		max_period_size = rounddown_pow_of_two(max_period_size);

		if (oss_period_size > max_period_size)

			oss_period_size = max_period_size;

	}



	oss_periods = oss_buffer_size / oss_period_size;

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