* bug report: aloop: potential signedness bug in loopback_prepare()
@ 2010-10-09 11:42 Dan Carpenter
2010-10-09 12:14 ` Jaroslav Kysela
0 siblings, 1 reply; 3+ messages in thread
From: Dan Carpenter @ 2010-10-09 11:42 UTC (permalink / raw)
To: Jaroslav Kysela; +Cc: alsa-devel
Hi Jaroslav,
sound/drivers/aloop.c +287 loopback_prepare(10)
warn: bogus compare against zero: 'bps'
282 unsigned int bps, salign;
283
284 salign = (snd_pcm_format_width(runtime->format) *
285 runtime->channels) / 8;
286 bps = salign * runtime->rate;
287 if (bps <= 0 || salign <= 0)
^^^^^^^^^^^^^^^^^^^^^^^
Both "bps" and "salign" are unsigned and are never less than
zero. Should this just be checking for == 0? Or was the check
supposed to catch integer overflows?
288 return -EINVAL;
289
regards,
dan carpenter
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: bug report: aloop: potential signedness bug in loopback_prepare()
2010-10-09 11:42 bug report: aloop: potential signedness bug in loopback_prepare() Dan Carpenter
@ 2010-10-09 12:14 ` Jaroslav Kysela
2010-10-09 14:58 ` Dan Carpenter
0 siblings, 1 reply; 3+ messages in thread
From: Jaroslav Kysela @ 2010-10-09 12:14 UTC (permalink / raw)
To: Dan Carpenter; +Cc: ALSA development
On Sat, 9 Oct 2010, Dan Carpenter wrote:
> Hi Jaroslav,
>
> sound/drivers/aloop.c +287 loopback_prepare(10)
> warn: bogus compare against zero: 'bps'
> 282 unsigned int bps, salign;
> 283
> 284 salign = (snd_pcm_format_width(runtime->format) *
> 285 runtime->channels) / 8;
> 286 bps = salign * runtime->rate;
> 287 if (bps <= 0 || salign <= 0)
> ^^^^^^^^^^^^^^^^^^^^^^^
>
>
> Both "bps" and "salign" are unsigned and are never less than
> zero. Should this just be checking for == 0? Or was the check
> supposed to catch integer overflows?
The condition works for both signed and unsigned values. That was only
reason why I did not write '==' there.
Jaroslav
-----
Jaroslav Kysela <perex@perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: bug report: aloop: potential signedness bug in loopback_prepare()
2010-10-09 12:14 ` Jaroslav Kysela
@ 2010-10-09 14:58 ` Dan Carpenter
0 siblings, 0 replies; 3+ messages in thread
From: Dan Carpenter @ 2010-10-09 14:58 UTC (permalink / raw)
To: Jaroslav Kysela; +Cc: ALSA development
On Sat, Oct 09, 2010 at 02:14:30PM +0200, Jaroslav Kysela wrote:
> On Sat, 9 Oct 2010, Dan Carpenter wrote:
>
>> Hi Jaroslav,
>>
>> sound/drivers/aloop.c +287 loopback_prepare(10)
>> warn: bogus compare against zero: 'bps'
>> 282 unsigned int bps, salign;
>> 283
>> 284 salign = (snd_pcm_format_width(runtime->format) *
>> 285 runtime->channels) / 8;
>> 286 bps = salign * runtime->rate;
>> 287 if (bps <= 0 || salign <= 0)
>> ^^^^^^^^^^^^^^^^^^^^^^^
>>
>>
>> Both "bps" and "salign" are unsigned and are never less than
>> zero. Should this just be checking for == 0? Or was the check
>> supposed to catch integer overflows?
>
> The condition works for both signed and unsigned values. That was only
> reason why I did not write '==' there.
>
> Jaroslav
>
What I mean is that the less than zero part is never true. For example,
the following test program will print "more" instead of "less".
regards,
dan carpenter
#include <stdio.h>
int main(int argc, char **argv)
{
unsigned int x = -3;
if (x <= 0)
printf("less\n");
else
printf("more\n");
return 0;
}
^ permalink raw reply [flat|nested] 3+ messages in thread
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2010-10-09 11:42 bug report: aloop: potential signedness bug in loopback_prepare() Dan Carpenter
2010-10-09 12:14 ` Jaroslav Kysela
2010-10-09 14:58 ` Dan Carpenter
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