On 01/25/2018 03:36 PM, Michael S. Tsirkin wrote: > This reverts commit bcecb4bbf88aa03171c30652bca761cf27755a6b. > > If we try to allocate an extra entry as the above commit did, and when > the requested size is UINT_MAX, addition overflows causing zero size to > be passed to kmalloc(). > > kmalloc then returns ZERO_SIZE_PTR with a subsequent crash. > > Reported-by: [email protected] > Cc: John Fastabend <[email protected]> > Signed-off-by: Michael S. Tsirkin <[email protected]> > ---
Dang, I missed this case. Thanks. Acked-by: John Fastabend <[email protected]> > include/linux/ptr_ring.h | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h > index f175846..3a19ebd 100644 > --- a/include/linux/ptr_ring.h > +++ b/include/linux/ptr_ring.h > @@ -466,12 +466,7 @@ 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) > { > - /* Allocate an extra dummy element at end of ring to avoid consumer head > - * or produce head access past the end of the array. Possible when > - * producer/consumer operations and __ptr_ring_peek operations run in > - * parallel. > - */ > - return kcalloc(size + 1, sizeof(void *), gfp); > + return kcalloc(size, sizeof(void *), gfp); > } > > static inline void __ptr_ring_set_size(struct ptr_ring *r, int size) >
