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Commit e5531662 authored by Cong Wang's avatar Cong Wang Committed by Greg Kroah-Hartman
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ptr_ring: wrap back ->producer in __ptr_ring_swap_queue() 



[ Upstream commit aff6db454599d62191aabc208930e891748e4322 ]

__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: default avatar <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: default avatarCong Wang <xiyou.wangcong@gmail.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 41783853

include/linux/ptr_ring.h

+2 −0
Original line number Diff line number Diff line
@@ -551,6 +551,8 @@ 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;