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: syzbot+87678bcf753b44c39...@syzkaller.appspotmail.com
Cc: John Fastabend <john.fastab...@gmail.com>
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
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)
--
MST
