[patch] bus error in gcry_free

[Christian Biere]

Werner Koch wrote:
> On Thu,  1 Feb 2007 14:34, christianbiere at gmx.de said:
> 
> > This patch is nonsense. It may work if you cast to size_t or unsigned long.
> 
> Huh?
> 
>   return (pool_okay
>           && p >= pool
>           && p < (const void*)((const char*)pool+pool_size));
> 

If p points into the pool or just one byte after it, everything is fine and
well-defined. Otherwise, the behaviour of this code is completely undefined.
A compile may optimize this into this:

   return pool_okay && p != (const void*)((const char*)pool+pool_size);

That's probably not what you meant.

> I agree that the casts are not required but they don't harm either.
> Actually I committed this:

>   int
>   _gcry_private_is_secure (const void *p)
>   {
>     return (pool_okay
>             && p >= pool
>             && p <  pool+pool_size);
>   }

Then you've been GCCed. pointer arithmetic with "void *" is not covered by
any C standard and usually GCC warns about this.

>   ((char*)((memblock_t*) ((char*)p - BLOCK_HEAD_SIZE)) - (char*)pool)
>    < pool_size
> 
> As you can see we can easily get an address wrap here:

Yes, that's obviously wrong too.

-- 
Christian