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SubjectRe: [PATCH net] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
On Wed, Feb 07, 2018 at 04:08:25PM +0800, Jason Wang wrote:
> To avoid slab to warn about exceeded size, fail early if queue
> occupies more than KMALLOC_MAX_SIZE.
>
> Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> include/linux/ptr_ring.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> index 1883d61..4b862da 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -466,6 +466,8 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
>
> static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
> {
> + if (size > KMALLOC_MAX_SIZE)
> + return NULL;
> return kcalloc(size, sizeof(void *), gfp);
> }

I guess this approach does begin to make more sense
at least as a temporary stop-gap.

But does this actually prevent the crash in all cases?

size is in void* entry units, KMALLOC_MAX_SIZE is in bytes.


>
> --
> 2.7.4

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