Commit 9fb582b6 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller
Browse files

Revert "net: ptr_ring: otherwise safe empty checks can overrun array bounds"

This reverts commit bcecb4bb

.

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+87678bcf753b44c39b67@syzkaller.appspotmail.com
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84328342
......@@ -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)
......
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