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net/x25: Fix x25_neigh refcnt leak when receiving frame 

[ Upstream commit f35d12971b4d814cdb2f659d76b42f0c545270b6 ]

x25_lapb_receive_frame() invokes x25_get_neigh(), which returns a
reference of the specified x25_neigh object to "nb" with increased
refcnt.

When x25_lapb_receive_frame() returns, local variable "nb" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one path of
x25_lapb_receive_frame(). When pskb_may_pull() returns false, the
function forgets to decrease the refcnt increased by x25_get_neigh(),
causing a refcnt leak.

Fix this issue by calling x25_neigh_put() when pskb_may_pull() returns
false.

Fixes: cb101ed2c3 ("x25: Handle undersized/fragmented skbs")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiyu Yang 2020-04-23 13:13:03 +08:00 committed by Greg Kroah-Hartman
parent 6885d58eb4
commit 5a2ddf8e5a
1 changed files with 3 additions and 1 deletions
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4
net/x25/x25_dev.c
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@ -115,8 +115,10 @@ int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
goto drop;
}
if (!pskb_may_pull(skb, 1))
if (!pskb_may_pull(skb, 1)) {
x25_neigh_put(nb);
return 0;
}
switch (skb->data[0]) {