Re: 2.6.14 kernels and above copy_to_user stupidity with IRQ disabled check

["Jeff V. Merkey" <jmerkey@wolfmountaingroup.com>]

Phillip Susi wrote:

> jmerkey@ns1.utah-nac.org wrote:
>
> > OK.  Got it.  I guess I need to restructure.  And BTW, This was a 
> > code fragment
> > only, the spinlock gets released when -EFAULT is called -- was just 
> > an example.
> >
> > Jeff
>
>
> Unless you have redefined EFAULT in some strange and hideous way, it 
> is not "called" and doesn't free the spinlock.  EFAULT is defined as a 
> literal integer, so you're just returning a number without freeing the 
> spinlock.
>
> If you have redefined EFAULT to a macro function call or whatever, 
> then don't do that, it's REALLY horrible coding practice.
No.  I posted a code fragment as an example.  Here's the actual code:

int dump_regen(VIRTUAL_SETUP *s, ULONG count)
{
   register int i = 0;
   VIRTUAL_SETUP *v;
                                                                               

   spin_lock_irqsave(&regen_lock, regen_flags);
   v = regen_head;
   while (v)
   {
      if (i >= count)
      {
         spin_unlock_irqrestore(&regen_lock, regen_flags);
         return -EFAULT;
      }
                                                                               

      err = copy_to_user(&s[i++], v, sizeof(VIRTUAL_SETUP));
      if (err)
      {         
          spin_unlock_irqrestore(&regen_lock, regen_flags);
          return err;
      }

      v = v->next;
   }
   spin_unlock_irqrestore(&regen_lock, regen_flags);
   return 0;
}

Needless to say, this has been restructured to this:

int dump_regen(VIRTUAL_SETUP *s, ULONG count)
{
   register int i = 0;
   VIRTUAL_SETUP *v;
                                                                               

   spin_lock_irqsave(&regen_lock, regen_flags);
   v = regen_head;
   while (v)
   {
      if (i >= count)
      {
         spin_unlock_irqrestore(&regen_lock, regen_flags);
         return 0;
      }
                                                                               

      P_Copy(&s[i++], v, sizeof(VIRTUAL_SETUP));
      v = v->next;
   }
   spin_unlock_irqrestore(&regen_lock, regen_flags);
   return 0;
}
                                                                               

Jeff

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/