* [patch] oss/sb_audio: prevent divide by zero bug
@ 2012-08-18 15:55 Dan Carpenter
2012-08-20 8:24 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Dan Carpenter @ 2012-08-18 15:55 UTC (permalink / raw)
To: Jaroslav Kysela; +Cc: Takashi Iwai, alsa-devel, kernel-janitors
Speed comes from get_user() in audio_ioctl(). We use it to set the "s"
variable before clamping it to valid values so it could lead to a divide
by zero bug.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
diff --git a/sound/oss/sb_audio.c b/sound/oss/sb_audio.c
index 733b014..b2b3c01 100644
--- a/sound/oss/sb_audio.c
+++ b/sound/oss/sb_audio.c
@@ -575,13 +575,15 @@ static int jazz16_audio_set_speed(int dev, int speed)
if (speed > 0)
{
int tmp;
- int s = speed * devc->channels;
+ int s;
if (speed < 5000)
speed = 5000;
if (speed > 44100)
speed = 44100;
+ s = speed * devc->channels;
+
devc->tconst = (256 - ((1000000 + s / 2) / s)) & 0xff;
tmp = 256 - devc->tconst;
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [patch] oss/sb_audio: prevent divide by zero bug
2012-08-18 15:55 [patch] oss/sb_audio: prevent divide by zero bug Dan Carpenter
@ 2012-08-20 8:24 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2012-08-20 8:24 UTC (permalink / raw)
To: Dan Carpenter; +Cc: alsa-devel, kernel-janitors
At Sat, 18 Aug 2012 18:55:15 +0300,
Dan Carpenter wrote:
>
> Speed comes from get_user() in audio_ioctl(). We use it to set the "s"
> variable before clamping it to valid values so it could lead to a divide
> by zero bug.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Thanks, applied now.
Takashi
> diff --git a/sound/oss/sb_audio.c b/sound/oss/sb_audio.c
> index 733b014..b2b3c01 100644
> --- a/sound/oss/sb_audio.c
> +++ b/sound/oss/sb_audio.c
> @@ -575,13 +575,15 @@ static int jazz16_audio_set_speed(int dev, int speed)
> if (speed > 0)
> {
> int tmp;
> - int s = speed * devc->channels;
> + int s;
>
> if (speed < 5000)
> speed = 5000;
> if (speed > 44100)
> speed = 44100;
>
> + s = speed * devc->channels;
> +
> devc->tconst = (256 - ((1000000 + s / 2) / s)) & 0xff;
>
> tmp = 256 - devc->tconst;
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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