[PATCH] ALSA: rockchip_i2s: fix a possible divide-by-zero bug in rockchip_i2s_hw_params()

[PATCH] ALSA: rockchip_i2s: fix a possible divide-by-zero bug in rockchip_i2s_hw_params()

[Tuo Li]

The variable bclk_rate is checked in:
  if (bclk_rate && mclk_rate % bclk_rate)

This indicates that bclk_rate can be zero.
If so, a divide-by-zero bug will occur:
  div_bclk = mclk_rate / bclk_rate;

To fix this possible bug, the function returns -EINVAL when bclk_rate is
zero.

Signed-off-by: Tuo Li <tuoli96@outlook.com>
---
 sound/soc/rockchip/rockchip_i2s.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index d1438753edb4..593299675b8c 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -279,7 +279,7 @@ static int rockchip_i2s_hw_params(struct snd_pcm_substream *substream,
 	if (i2s->is_master_mode) {
 		mclk_rate = clk_get_rate(i2s->mclk);
 		bclk_rate = 2 * 32 * params_rate(params);
-		if (bclk_rate && mclk_rate % bclk_rate)
+		if (bclk_rate == 0 || mclk_rate % bclk_rate)
 			return -EINVAL;
 
 		div_bclk = mclk_rate / bclk_rate;
-- 
2.17.1


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Re: [PATCH] ALSA: rockchip_i2s: fix a possible divide-by-zero bug in rockchip_i2s_hw_params()

[Mark Brown]

On Mon, 7 Sep 2020 21:09:37 +0800, Tuo Li wrote:
> The variable bclk_rate is checked in:
>   if (bclk_rate && mclk_rate % bclk_rate)
> 
> This indicates that bclk_rate can be zero.
> If so, a divide-by-zero bug will occur:
>   div_bclk = mclk_rate / bclk_rate;
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ALSA: rockchip_i2s: fix a possible divide-by-zero bug in rockchip_i2s_hw_params()
      commit: 375e2c352582442783178e6a33c279d6bc9354a2

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

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