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dtls.c: fix oob read in dtls_get_cookie. #280

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dtls.c: fix oob read in dtls_get_cookie. #280

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12 changes: 7 additions & 5 deletions dtls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -437,6 +437,8 @@ dtls_write(struct dtls_context_t *ctx, session_t *session,

static int
dtls_get_cookie(uint8 *msg, size_t msglen, uint8 **cookie) {
uint8_t cookie_length = 0;

/* To access the cookie, we have to determine the session id's
* length and skip the whole thing. */
if (msglen < DTLS_HS_LENGTH + DTLS_CH_LENGTH + sizeof(uint8))
Expand All @@ -452,11 +454,11 @@ dtls_get_cookie(uint8 *msg, size_t msglen, uint8 **cookie) {
SKIP_VAR_FIELD(msg, msglen, uint8, DTLS_ALERT_HANDSHAKE_FAILURE,
"get_cookie, session_id");

if (msglen < (*msg & 0xff) + sizeof(uint8))
return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);

*cookie = msg + sizeof(uint8);
return dtls_uint8_to_int(msg);
/* get cookie field */
GET_VAR_FIELD(cookie_length, msg, msglen, uint8, DTLS_ALERT_HANDSHAKE_FAILURE,
"get_cookie, cookie")
*cookie = msg;
return cookie_length;
}

static int
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