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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 05:17:59PM +0800, Jason Wang wrote:
>
>
> On 2018年02月07日 16:08, 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);
> > }
>
> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")

That's probably not enough. How about switching to kvmalloc and limiting
this drastically to e.g. 64K. I vaguely remember that some wise man said
that should be enough for everybody :)

--
MST

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