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Fix for CVE-2015-0291

If a client renegotiates using an invalid signature algorithms extension
it will crash a server with a NULL pointer dereference.

Thanks to David Ramos of Stanford University for reporting this bug.

CVE-2015-0291

Reviewed-by: Tim Hudson <tjh@openssl.org>
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snhenson authored and mattcaswell committed Mar 3, 2015
1 parent 09f0692 commit 34e3edbf3a10953cb407288101fd56a629af22f9
Showing with 10 additions and 6 deletions.
  1. +10 −6 ssl/t1_lib.c
@@ -2693,6 +2693,7 @@ int tls1_set_server_sigalgs(SSL *s)
if (s->cert->shared_sigalgs) {
OPENSSL_free(s->cert->shared_sigalgs);
s->cert->shared_sigalgs = NULL;
s->cert->shared_sigalgslen = 0;
}
/* Clear certificate digests and validity flags */
for (i = 0; i < SSL_PKEY_NUM; i++) {
@@ -3396,6 +3397,7 @@ static int tls1_set_shared_sigalgs(SSL *s)
if (c->shared_sigalgs) {
OPENSSL_free(c->shared_sigalgs);
c->shared_sigalgs = NULL;
c->shared_sigalgslen = 0;
}
/* If client use client signature algorithms if not NULL */
if (!s->server && c->client_sigalgs && !is_suiteb) {
@@ -3418,12 +3420,14 @@ static int tls1_set_shared_sigalgs(SSL *s)
preflen = c->peer_sigalgslen;
}
nmatch = tls12_shared_sigalgs(s, NULL, pref, preflen, allow, allowlen);
if (!nmatch)
return 1;
salgs = OPENSSL_malloc(nmatch * sizeof(TLS_SIGALGS));
if (!salgs)
return 0;
nmatch = tls12_shared_sigalgs(s, salgs, pref, preflen, allow, allowlen);
if (nmatch) {
salgs = OPENSSL_malloc(nmatch * sizeof(TLS_SIGALGS));
if (!salgs)
return 0;
nmatch = tls12_shared_sigalgs(s, salgs, pref, preflen, allow, allowlen);
} else {
salgs = NULL;
}
c->shared_sigalgs = salgs;
c->shared_sigalgslen = nmatch;
return 1;

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