tree d4c5b340e42fb7cca4d1a5282669ffae94227fdc
parent 7c3ceb4fb9667f34f1599a062efecf4cdc4a4ce5
author Vladislav Yasevich <vladsilav.yasevich@hp.com> 1146873829 -0700
committer David S. Miller <davem@davemloft.net> 1146873829 -0700

[SCTP]: Prevent possible infinite recursion with multiple bundled DATA.

There is a rare situation that causes lksctp to go into infinite recursion
and crash the system.  The trigger is a packet that contains at least the
first two DATA fragments of a message bundled together. The recursion is
triggered when the user data buffer is smaller that the full data message.
The problem is that we clone the skb for every fragment in the message.
When reassembling the full message, we try to link skbs from the "first
fragment" clone using the frag_list. However, since the frag_list is shared
between two clones in this rare situation, we end up setting the frag_list
pointer of the second fragment to point to itself.  This causes
sctp_skb_pull() to potentially recurse indefinitely.

Proposed solution is to make a copy of the skb when attempting to link
things using frag_list.

Signed-off-by: Vladislav Yasevich <vladsilav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>