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Fix a couple of issues in DTLS ClientHello parsing. #11007

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Fix a couple of issues in DTLS ClientHello parsing. #11007

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834db02
Fix a couple of issues in DTLS ClientHello parsing.
kareem-wolfssl Jul 29, 2026
706f38c
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kareem-wolfssl Jul 31, 2026
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27 changes: 20 additions & 7 deletions src/tls13.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7363,39 +7363,48 @@ static int DoTls13SupportedVersions(WOLFSSL* ssl, const byte* input, word32 i,

/* Client random */
i += RAN_LEN;

if (i > helloSz)
return BUFFER_ERROR;
/* Session id - not used in TLS v1.3 */
if (helloSz - i < OPAQUE8_LEN) {
return BUFFER_ERROR;
}
b = input[i++];
if (i + b > helloSz) {
if (b > helloSz - i) {
return BUFFER_ERROR;
}
i += b;
#ifdef WOLFSSL_DTLS13
if (ssl->options.dtls) {
/* legacy_cookie - not used in DTLS v1.3 */
if (helloSz - i < OPAQUE8_LEN) {
return BUFFER_ERROR;
}
b = input[i++];
if (i + b > helloSz) {
if (b > helloSz - i) {
return BUFFER_ERROR;
}
i += b;
}
#endif /* WOLFSSL_DTLS13 */
/* Cipher suites */
if (i + OPAQUE16_LEN > helloSz)
if (helloSz - i < OPAQUE16_LEN)
return BUFFER_ERROR;
ato16(input + i, &suiteSz);
i += OPAQUE16_LEN;
if (i + suiteSz + 1 > helloSz)
if ((word32)suiteSz + OPAQUE8_LEN > helloSz - i)
return BUFFER_ERROR;
i += suiteSz;
/* Compression */
b = input[i++];
if (i + b > helloSz)
if (b > helloSz - i)
return BUFFER_ERROR;
i += b;

/* TLS 1.3 must have extensions */
if (i < helloSz) {
if (i + OPAQUE16_LEN > helloSz)
if (helloSz - i < OPAQUE16_LEN)
return BUFFER_ERROR;
ato16(&input[i], &totalExtSz);
i += OPAQUE16_LEN;
Expand Down Expand Up @@ -7745,8 +7754,12 @@ int DoTls13ClientHello(WOLFSSL* ssl, const byte* input, word32* inOutIdx,
#ifdef WOLFSSL_DTLS13
/* legacy_cookie */
if (ssl->options.dtls) {
word32 rel = args->idx - args->begin;
byte cookieLen;
if (rel > helloSz || helloSz - rel < OPAQUE8_LEN)
ERROR_OUT(BUFFER_ERROR, exit_dch);
/* https://www.rfc-editor.org/rfc/rfc9147.html#section-5.3 */
byte cookieLen = input[args->idx++];
cookieLen = input[args->idx++];
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if (cookieLen != 0) {
ERROR_OUT(INVALID_PARAMETER, exit_dch);
}
Expand Down
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