[next] ASoC: cx2072x: fix integer overflow on unsigned int multiply

Commit Message

Colin King May 24, 2019, 10:25 p.m. UTC

From: Colin Ian King <[e-mail]>

In the case where frac_div larger than 96 the result of an unsigned
multiplication overflows an unsigned int.  For example, this can
happen when the sample_rate is 192000 and pll_input is 122.  Fix
this by casing the first term of the mutiply to a u64. Also remove
the extraneous parentheses around the expression.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: a497a4363706 ("ASoC: Add support for Conexant CX2072X CODEC")
Signed-off-by: Colin Ian King <[e-mail]>
---
 sound/soc/codecs/cx2072x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Takashi Iwai May 25, 2019, 6:25 a.m. UTC | #1

On Sat, 25 May 2019 00:25:51 +0200,
Colin King wrote:
> 
> From: Colin Ian King <[e-mail]>
> 
> In the case where frac_div larger than 96 the result of an unsigned
> multiplication overflows an unsigned int.  For example, this can
> happen when the sample_rate is 192000 and pll_input is 122.  Fix
> this by casing the first term of the mutiply to a u64. Also remove
> the extraneous parentheses around the expression.
> 
> Addresses-Coverity: ("Unintentional integer overflow")
> Fixes: a497a4363706 ("ASoC: Add support for Conexant CX2072X CODEC")
> Signed-off-by: Colin Ian King <[e-mail]>

Reviewed-by: Takashi Iwai <[e-mail]>


thanks,

Takashi

Patch

diff --git a/sound/soc/codecs/cx2072x.c b/sound/soc/codecs/cx2072x.c
index c11a585bbf70..e8e6fd2e97b6 100644
--- a/sound/soc/codecs/cx2072x.c
+++ b/sound/soc/codecs/cx2072x.c
@@ -627,7 +627,7 @@  static int cx2072x_config_pll(struct cx2072x_priv *cx2072x)
 	if (frac_div) {
 		frac_div *= 1000;
 		frac_div /= pll_input;
-		frac_num = ((4000 + frac_div) * ((1 << 20) - 4));
+		frac_num = (u64)(4000 + frac_div) * ((1 << 20) - 4);
 		do_div(frac_num, 7);
 		frac = ((u32)frac_num + 499) / 1000;
 	}