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TLS: Avoid undefined behavior in pointer arithmetic

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Reorder terms in a way that no invalid pointers are generated with
pos+len operations. end-pos is always defined (with a valid pos pointer)
while pos+len could end up pointing beyond the end pointer which would
be undefined behavior.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-10-18 17:28:35 +03:00
parent 2461724c05
commit d2eb91e08f
3 changed files with 32 additions and 16 deletions
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16
src/tls/tlsv1_client_write.c
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@ -134,6 +134,11 @@ static int tls_write_client_certificate(struct tlsv1_client *conn,
struct x509_certificate *cert;
pos = *msgpos;
if (TLS_RECORD_HEADER_LEN + 1 + 3 + 3 > end - pos) {
tls_alert(conn, TLS_ALERT_LEVEL_FATAL,
TLS_ALERT_INTERNAL_ERROR);
return -1;
}
wpa_printf(MSG_DEBUG, "TLSv1: Send Certificate");
rhdr = pos;
@ -154,7 +159,7 @@ static int tls_write_client_certificate(struct tlsv1_client *conn,
pos += 3;
cert = conn->cred ? conn->cred->cert : NULL;
while (cert) {
if (pos + 3 + cert->cert_len > end) {
if (3 + cert->cert_len > (size_t) (end - pos)) {
wpa_printf(MSG_DEBUG, "TLSv1: Not enough buffer space "
"for Certificate (cert_len=%lu left=%lu)",
(unsigned long) cert->cert_len,
@ -265,9 +270,16 @@ static int tlsv1_key_x_dh(struct tlsv1_client *conn, u8 **pos, u8 *end)
wpa_hexdump(MSG_DEBUG, "TLSv1: DH Yc (client's public value)",
dh_yc, dh_yc_len);
if (end - *pos < 2) {
tls_alert(conn, TLS_ALERT_LEVEL_FATAL,
TLS_ALERT_INTERNAL_ERROR);
os_free(csecret);
os_free(dh_yc);
return -1;
}
WPA_PUT_BE16(*pos, dh_yc_len);
*pos += 2;
if (*pos + dh_yc_len > end) {
if (dh_yc_len > (size_t) (end - *pos)) {
wpa_printf(MSG_DEBUG, "TLSv1: Not enough room in the "
"message buffer for Yc");
tls_alert(conn, TLS_ALERT_LEVEL_FATAL,