[PATCH 3.4 11/23] tipc: clear next-pointer of message fragments before reassembly

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jon Paul Maloy <jon.maloy@xxxxxxxxxxxx>

[ Upstream commit 999417549c16dd0e3a382aa9f6ae61688db03181 ]

If the 'next' pointer of the last fragment buffer in a message is not
zeroed before reassembly, we risk ending up with a corrupt message,
since the reassembly function itself isn't doing this.

Currently, when a buffer is retrieved from the deferred queue of the
broadcast link, the next pointer is not cleared, with the result as
described above.

This commit corrects this, and thereby fixes a bug that may occur when
long broadcast messages are transmitted across dual interfaces. The bug
has been present since 40ba3cdf542a469aaa9083fa041656e59b109b90 ("tipc:
message reassembly using fragment chain")

This commit should be applied to both net and net-next.

Signed-off-by: Jon Maloy <jon.maloy@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/tipc/bcast.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -541,6 +541,7 @@ receive:
 
 		buf = node->bclink.deferred_head;
 		node->bclink.deferred_head = buf->next;
+		buf->next = NULL;
 		node->bclink.deferred_size--;
 		goto receive;
 	}


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