On Tue, 2015-03-24 at 13:46 -0700, Michael Opdenacker wrote:
> Hi,
>
> On 03/22/2015 11:59 PM, Hannes Reinecke wrote:
> > On 03/22/2015 05:31 PM, Michael Opdenacker wrote:
> >> This replaces kmalloc + memset by a call to kzalloc
> >> (or kcalloc when appropriate, which zeroes memory too)
> >>
> >> This also fixes one checkpatch.pl issue in the process.
> >>
> >> This improvement was suggested by "make coccicheck"
> >>
> >> Signed-off-by: Michael Opdenacker <michael.opdenacker@xxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
>
> I'm sending a version that reverts the use of kcalloc() instead of
> kzalloc(). For reasons I don't understand, I didn't see the end of
> Robert Elliott's comment that the use of kcalloc() could prevent the
> compiler from detecting an overflow.
I'm confused. I don't see that comment either, but
the entire point of kcalloc is to prevent overflows
by returning NULL when an overflow might occur.
from include/linux/slab.h:
/**
* kmalloc_array - allocate memory for an array.
* @n: number of elements.
* @size: element size.
* @flags: the type of memory to allocate (see kmalloc).
*/
static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
{
if (size != 0 && n > SIZE_MAX / size)
return NULL;
return __kmalloc(n * size, flags);
}
/**
* kcalloc - allocate memory for an array. The memory is set to zero.
* @n: number of elements.
* @size: element size.
* @flags: the type of memory to allocate (see kmalloc).
*/
static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
{
return kmalloc_array(n, size, flags | __GFP_ZERO);
}
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