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authorCong Wang <xiyou.wangcong@gmail.com>2018-12-30 12:43:42 -0800
committerDavid S. Miller <davem@davemloft.net>2019-01-01 11:58:33 -0800
commitaff6db454599d62191aabc208930e891748e4322 (patch)
tree1c26fd35a8fc7540bb81ca60fe96251c74e71b36
parent4087d2bc0d9469835f8d19d63a4a56739e5b8c5b (diff)
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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: 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>
-rw-r--r--include/linux/ptr_ring.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 6894976b54e3..186cd8e970c7 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -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;