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

[ 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@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 716de1ac6cb560c8cc55a257a0d76d39230634f3..6ef89256b2fb7fd5f1b73d7e3f8c9fb95f44c632 100644 (file)
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -531,6 +531,7 @@ receive:
 
                buf = node->bclink.deferred_head;
                node->bclink.deferred_head = buf->next;
+               buf->next = NULL;
                node->bclink.deferred_size--;
                goto receive;
        }