Re: [PATCH] alsa: fix comparison of unsigned < 0

[Takashi Iwai]

Hi,

thanks for checking this.
They seem actually hitting some real bugs.


At Wed, 30 May 2007 03:35:54 -0400,
Bill Nottingham wrote:
> 
> diff -ru linux-2.6.21-old/sound/pci/ac97/ac97_patch.c 
> linux-2.6.21/sound/pci/ac97/ac97_patch.c
> --- linux-2.6.21-old/sound/pci/ac97/ac97_patch.c      2007-05-30 
> 02:53:05.000000000 -0400
> +++ linux-2.6.21/sound/pci/ac97/ac97_patch.c  2007-05-30 02:32:41.000000000 
> -0400
> @@ -2086,8 +2086,7 @@
>       struct snd_ac97 *ac97 = snd_kcontrol_chip(kcontrol);
>       unsigned short val;
>  
> -     if (ucontrol->value.enumerated.item[0] > 3
> -         || ucontrol->value.enumerated.item[0] < 0)
> +     if (ucontrol->value.enumerated.item[0] > 3)
>               return -EINVAL;
>       val = ctrl2reg[ucontrol->value.enumerated.item[0]]
>             << AC97_AD198X_VREF_SHIFT;

This one is fine.


> diff -ru linux-2.6.21-old/sound/pci/ali5451/ali5451.c 
> linux-2.6.21/sound/pci/ali5451/ali5451.c
> --- linux-2.6.21-old/sound/pci/ali5451/ali5451.c      2007-05-30 
> 02:53:05.000000000 -0400
> +++ linux-2.6.21/sound/pci/ali5451/ali5451.c  2007-05-30 02:33:27.000000000 
> -0400
> @@ -2057,10 +2057,8 @@
>  {
>       if (codec->hw_initialized)
>               snd_ali_disable_address_interrupt(codec);
> -     if (codec->irq >= 0) {
> -             synchronize_irq(codec->irq);
> -             free_irq(codec->irq, codec);
> -     }
> +     synchronize_irq(codec->irq);
> +     free_irq(codec->irq, codec);
>       if (codec->port)
>               pci_release_regions(codec->pci);
>       pci_disable_device(codec->pci);

Bah, the check isn't wrong but the type of codec->irq.
It should be int instead of unsigned long.  I'll fix it.


> diff -ru linux-2.6.21-old/sound/pci/ca0106/ca0106_proc.c 
> linux-2.6.21/sound/pci/ca0106/ca0106_proc.c
> --- linux-2.6.21-old/sound/pci/ca0106/ca0106_proc.c   2007-05-30 
> 02:53:05.000000000 -0400
> +++ linux-2.6.21/sound/pci/ca0106/ca0106_proc.c       2007-05-30 
> 02:34:19.000000000 -0400
> @@ -305,7 +305,7 @@
>          while (!snd_info_get_line(buffer, line, sizeof(line))) {
>                  if (sscanf(line, "%x %x", &reg, &val) != 2)
>                          continue;
> -                if ((reg < 0x40) && (reg >=0) && (val <= 0xffffffff) ) {
> +                if ((reg < 0x40) && (val <= 0xffffffff) ) {

It's a 32bit unsigned int, so the check of 0xffffffff isn't needed,
too.

>                       spin_lock_irqsave(&emu->emu_lock, flags);
>                       outl(val, emu->port + (reg & 0xfffffffc));
>                       spin_unlock_irqrestore(&emu->emu_lock, flags);
> @@ -406,7 +406,7 @@
>          while (!snd_info_get_line(buffer, line, sizeof(line))) {
>                  if (sscanf(line, "%x %x %x", &reg, &channel_id, &val) != 3)
>                          continue;
> -                if ((reg < 0x80) && (reg >=0) && (val <= 0xffffffff) && 
> (channel_id >=0) && (channel_id <= 3) )
> +                if ((reg < 0x80) && (val <= 0xffffffff) && (channel_id <= 3) 
> )
>                          snd_ca0106_ptr_write(emu, reg, channel_id, val);
>          }
>  }

Ditto.


> diff -ru linux-2.6.21-old/sound/pci/rme9652/rme9652.c 
> linux-2.6.21/sound/pci/rme9652/rme9652.c
> --- linux-2.6.21-old/sound/pci/rme9652/rme9652.c      2007-05-30 
> 02:53:05.000000000 -0400
> +++ linux-2.6.21/sound/pci/rme9652/rme9652.c  2007-05-30 02:35:16.000000000 
> -0400
> @@ -406,8 +406,6 @@
>               } else if (!frag)
>                       return 0;
>               offset -= rme9652->max_jitter;
> -             if (offset < 0)
> -                     offset += period_size * 2;

I think this check is actually needed, but it must be cast to int.
Will fix this, too.


Takashi
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