Based on comments from Xin, even after fixes for our recent syzbot
report of cookie memory leaks, its possible to get a resend of an INIT
chunk which would lead to us leaking cookie memory.

To ensure that we don't leak cookie memory, free any previously
allocated cookie first.

Signed-off-by: Neil Horman <nhor...@tuxdriver.com>
CC: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
CC: Xin Long <lucien....@gmail.com>
CC: "David S. Miller" <da...@davemloft.net>
CC: netdev@vger.kernel.org
---
 net/sctp/sm_make_chunk.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index f17908f5c4f3..21f7faf032e5 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -2583,6 +2583,8 @@ static int sctp_process_param(struct sctp_association 
*asoc,
        case SCTP_PARAM_STATE_COOKIE:
                asoc->peer.cookie_len =
                        ntohs(param.p->length) - sizeof(struct sctp_paramhdr);
+               if (asoc->peer.cookie)
+                       kfree(asoc->peer.cookie);
                asoc->peer.cookie = kmemdup(param.cookie->body, 
asoc->peer.cookie_len, gfp);
                if (!asoc->peer.cookie)
                        retval = 0;
-- 
2.20.1

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