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SubjectRe: integer overflows in kernel/relay.c
On Wed, 08 Feb 2012 09:34:16 +0100
Jens Axboe <axboe@kernel.dk> wrote:

> On 02/07/2012 03:11 PM, Dan Carpenter wrote:
> > My static checker is warning about integer overflows in kernel/relay.c
> >
> > relay_create_buf()
> > 170
> > 171 buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > This can only overflow on 32bit systems.
>
> Correct

This is a relatively common problem. Converting a kzalloc() call to
kcalloc() fixes it. But we do not have a non-zeroing version of
kcalloc().

Please, someone complete this patch and send it to me!


--- a/include/linux/slab.h~a
+++ a/include/linux/slab.h
@@ -240,11 +240,16 @@ size_t ksize(const void *);
* for general use, and so are not documented here. For a full list of
* potential flags, always refer to linux/gfp.h.
*/
-static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
+static inline void *wtf_do_i_call_this(size_t n, size_t size, gfp_t flags)
{
if (size != 0 && n > ULONG_MAX / size)
return NULL;
- return __kmalloc(n * size, flags | __GFP_ZERO);
+ return __kmalloc(n * size, flags);
+}
+
+static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
+{
+ return wtf_do_i_call_this(n, size, flags | __GFP_ZERO);
}

#if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
_


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