Re: [CHECKER][PATCH] awe_wave.c user pointer dereference

From: Hollis Blanchard (hollisb@us.ibm.com)
Date: Fri Jun 06 2003 - 11:31:22 EST


On Thursday, Jun 5, 2003, at 17:52 US/Central, Andrew Morton wrote:

> Hollis Blanchard <hollisb@us.ibm.com> wrote:
>>
>> + return -EFAULT;
>> return 0;
>> break;
>>
>> @@ -2063,10 +2064,12 @@
>>
>> case SNDCTL_SYNTH_MEMAVL:
>> return memsize - awe_free_mem_ptr() * 2;
>> + break;
>>
>> default:
>> printk(KERN_WARNING "AWE32: unsupported ioctl %d\n", cmd);
>> return -EINVAL;
>> + break;
>
> There's no need for a "break" after a "return"!

I've gotten a couple questions about that. :)

I did it for two reasons: 1) I'm a big fan of consistancy, and 3 of the
5 ioctl cases already had the break. 2) should the returns be replaced
with something like "retval = -EINVAL" and a single "return retval" at
the end of the function, I can easily imagine visually missing the need
for a break.

However, although a break after a return is fine with gcc -Wall, Joe
Perches informs me that it will annoy lint and the Intel compiler. So
here is the updated patch, which removes the (pre-existing! :) breaks
from the other cases.

-- 
Hollis Blanchard
IBM Linux Technology Center

===== sound/oss/awe_wave.c 1.12 vs edited ===== --- 1.12/sound/oss/awe_wave.c Thu Apr 3 16:35:48 2003 +++ edited/sound/oss/awe_wave.c Fri Jun 6 11:17:19 2003 @@ -2046,20 +2046,18 @@ awe_info.nr_voices = awe_max_voices; else awe_info.nr_voices = AWE_MAX_CHANNELS; - memcpy((char*)arg, &awe_info, sizeof(awe_info)); + if (copy_to_user((char*)arg, &awe_info, sizeof(awe_info))) + return -EFAULT; return 0; - break;

case SNDCTL_SEQ_RESETSAMPLES: awe_reset(dev); awe_reset_samples(); return 0; - break;

case SNDCTL_SEQ_PERCMODE: /* what's this? */ return 0; - break;

case SNDCTL_SYNTH_MEMAVL: return memsize - awe_free_mem_ptr() * 2; @@ -4314,7 +4312,8 @@ if (((cmd >> 8) & 0xff) != 'M') return -EINVAL;

- level = *(int*)arg; + if (get_user(level, (int *)arg)) + return -EFAULT; level = ((level & 0xff) + (level >> 8)) / 2; DEBUG(0,printk("AWEMix: cmd=%x val=%d\n", cmd & 0xff, level));

@@ -4370,7 +4369,9 @@ level = 0; break; } - return *(int*)arg = level; + if (put_user(level, (int *)arg)) + return -EFAULT; + return level; } #endif /* CONFIG_AWE32_MIXER */

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