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Fix Seg fault in DTLSv1_listen

The DTLSv1_listen function is intended to be stateless and processes
the initial ClientHello from many peers. It is common for user code to
loop over the call to DTLSv1_listen until a valid ClientHello is received
with an associated cookie. A defect in the implementation of DTLSv1_listen
means that state is preserved in the SSL object from one invokation to the
next that can lead to a segmentation fault. Erorrs processing the initial
ClientHello can trigger this scenario. An example of such an error could
be that a DTLS1.0 only client is attempting to connect to a DTLS1.2 only
server.

CVE-2015-0207

Reviewed-by: Richard Levitte <levitte@openssl.org>
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mattcaswell committed Mar 9, 2015
1 parent 1d2a18d commit e83ee04bb7de800cdb71d522fa562e99328003a3
Showing with 3 additions and 0 deletions.
  1. +3 −0 ssl/d1_lib.c
@@ -546,6 +546,9 @@ int dtls1_listen(SSL *s, struct sockaddr *client)
{
int ret;

/* Ensure there is no state left over from a previous invocation */
SSL_clear(s);

SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
s->d1->listen = 1;

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