tipc: fix potential bug in function tipc_backlog_rcv

In commit 4f4482dcd9a0606a30541ff165ddaca64748299b ("tipc: compensate
for double accounting in socket rcv buffer") we access 'truesize' of
a received buffer after it might have been released by the function
filter_rcv().

In this commit we correct this by reading the value of 'truesize' to
the stack before delivering the buffer to filter_rcv().

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 08d87fc80b10..ef0475568f9e 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1,5 +1,5 @@
 /*
-* net/tipc/socket.c: TIPC socket API
+ * net/tipc/socket.c: TIPC socket API
  *
  * Copyright (c) 2001-2007, 2012-2014, Ericsson AB
  * Copyright (c) 2004-2008, 2010-2013, Wind River Systems
@@ -1431,13 +1431,14 @@ static int tipc_backlog_rcv(struct sock *sk, struct sk_buff *buf)
 {
         u32 res;
         struct tipc_sock *tsk = tipc_sk(sk);
+        uint truesize = buf->truesize;
 
         res = filter_rcv(sk, buf);
         if (unlikely(res))
                 tipc_reject_msg(buf, res);
 
         if (atomic_read(&tsk->dupl_rcvcnt) < TIPC_CONN_OVERLOAD_LIMIT)
-                atomic_add(buf->truesize, &tsk->dupl_rcvcnt);
+                atomic_add(truesize, &tsk->dupl_rcvcnt);
 
         return 0;
 }