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ptr_ring: wrap back ->producer in __ptr_ring_swap_queue()

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[ 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: syzbot+8993c0fa96d57c399735@syzkaller.appspotmail.com
Fixes: 5d49de532002 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Cong Wang 2018-12-30 12:43:42 -08:00 committed by Greg Kroah-Hartman
parent 7abb7f747b
commit ce8ec03171
1 changed files with 2 additions and 0 deletions
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2
include/linux/ptr_ring.h
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@ -384,6 +384,8 @@ static inline void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
else if (destroy)
destroy(ptr);
if (producer >= size)
producer = 0;
r->size = size;
r->producer = producer;
r->consumer = 0;