tipc: clear 'next'-pointer of message fragments before reassembly

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

1 files changed, 1 insertions, 0 deletions

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 26631679a1fa..55c6c9d3e1ce 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -559,6 +559,7 @@ receive:
 
                 buf = node->bclink.deferred_head;
                 node->bclink.deferred_head = buf->next;
+                buf->next = NULL;
                 node->bclink.deferred_size--;
                 goto receive;
         }