Commit aff6db45 authored Dec 30, 2018 by Cong Wang Committed by David S. Miller Jan 01, 2019

ptr_ring: wrap back ->producer in __ptr_ring_swap_queue()



__ptr_ring_swap_queue() tries to move pointers from the old
ring to the new one, but it forgets to check if ->producer
is beyond the new size at the end of the operation. This leads
to an out-of-bound access in __ptr_ring_produce() as reported
by syzbot.

Reported-by:  <syzbot+8993c0fa96d57c399735@syzkaller.appspotmail.com>
Fixes: 5d49de53 ("ptr_ring: resize support")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 4087d2bc

include/linux/ptr_ring.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -573,6 +573,8 @@ static inline void *__ptr_ring_swap_queue(struct ptr_ring r, void **queue,
		else if (destroy)
		destroy(ptr);

		if (producer >= size)
		producer = 0;
		__ptr_ring_set_size(r, size);
		r->producer = producer;
		r->consumer_head = 0;

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