4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Cong Wang <xiyou.wangc...@gmail.com>
[ 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+8993c0fa96d57c399...@syzkaller.appspotmail.com
Fixes: 5d49de532002 ("ptr_ring: resize support")
Cc: "Michael S. Tsirkin" <m...@redhat.com>
Cc: John Fastabend <john.fastab...@gmail.com>
Cc: Jason Wang <jasow...@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
include/linux/ptr_ring.h | 2 ++
1 file changed, 2 insertions(+)
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -551,6 +551,8 @@ static inline void **__ptr_ring_swap_que
else if (destroy)
destroy(ptr);
+ if (producer >= size)
+ producer = 0;
__ptr_ring_set_size(r, size);
r->producer = producer;
r->consumer_head = 0;
