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Fix SRTP KDF null-idx crash and X509 DER length hardening #10212

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Fix SRTP KDF null-idx crash and X509 DER length hardening #10212

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f57a7b7
Fix SRTP KDF null-idx crash and X509 DER length hardening
ColtonWilley Apr 14, 2026
5bb246e
Add tests for X509 DER length guards
ColtonWilley Apr 28, 2026
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6 changes: 5 additions & 1 deletion src/x509.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4406,6 +4406,10 @@ const byte* wolfSSL_X509_get_der(WOLFSSL_X509* x509, int* outSz)
if (x509 == NULL || x509->derCert == NULL || outSz == NULL)
return NULL;

if (x509->derCert->length > (word32)INT_MAX) {
return NULL;
}

*outSz = (int)x509->derCert->length;
return x509->derCert->buffer;
}
Expand Down Expand Up @@ -8676,7 +8680,7 @@ int wolfSSL_i2d_X509(WOLFSSL_X509* x509, unsigned char** out)
}

der = wolfSSL_X509_get_der(x509, &derSz);
if (der == NULL) {
if (der == NULL || derSz <= 0) {
WOLFSSL_LEAVE("wolfSSL_i2d_X509", MEMORY_E);
return MEMORY_E;
}
Expand Down
113 changes: 112 additions & 1 deletion tests/api/test_ossl_x509_io.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@

#include <tests/unit.h>

#include <limits.h>

#ifdef NO_INLINE
#include <wolfssl/wolfcrypt/misc.h>
#else
Expand Down Expand Up @@ -72,6 +74,116 @@ int test_wolfSSL_i2d_X509(void)
return EXPECT_RESULT();
}

int test_wolfSSL_X509_get_der_length_guards(void)
{
EXPECT_DECLS;
#if defined(OPENSSL_EXTRA) && defined(USE_CERT_BUFFERS_2048) && !defined(NO_RSA)
const unsigned char* cert_buf = server_cert_der_2048;
const byte* der = NULL;
X509* cert = NULL;
const byte* origBuf = NULL;
word32 origLen = 0;
int derSz = 0;

ExpectNotNull(d2i_X509(&cert, &cert_buf, sizeof_server_cert_der_2048));
ExpectNotNull(cert);
ExpectNotNull(cert->derCert);
ExpectNotNull(cert->derCert->buffer);

if (EXPECT_SUCCESS()) {
origLen = cert->derCert->length;
origBuf = cert->derCert->buffer;
cert->derCert->length = (word32)INT_MAX;
der = wolfSSL_X509_get_der(cert, &derSz);
cert->derCert->length = origLen;
ExpectPtrEq(der, origBuf);
ExpectIntEQ(derSz, INT_MAX);

cert->derCert->length = ((word32)INT_MAX) + 1U;
der = wolfSSL_X509_get_der(cert, &derSz);
cert->derCert->length = origLen;
ExpectNull(der);

cert->derCert->length = 0;
der = wolfSSL_X509_get_der(cert, &derSz);
cert->derCert->length = origLen;
ExpectPtrEq(der, origBuf);
ExpectIntEQ(derSz, 0);

ExpectPtrEq(wolfSSL_X509_get_der(cert, &derSz), origBuf);
ExpectIntGT(derSz, 0);
}

X509_free(cert);
#endif
return EXPECT_RESULT();
}

int test_wolfSSL_i2d_X509_der_length_guards(void)
{
EXPECT_DECLS;
#if defined(OPENSSL_EXTRA) && defined(USE_CERT_BUFFERS_2048) && !defined(NO_RSA)
const unsigned char* cert_buf = server_cert_der_2048;
unsigned char* overflowOut = NULL;
unsigned char overflowBuf[4] = { 0x11, 0x22, 0x33, 0x44 };
const unsigned char overflowExpected[4] = { 0x11, 0x22, 0x33, 0x44 };
unsigned char* overflowCallerOut = overflowBuf;
unsigned char* zeroLenOut = NULL;
unsigned char zeroLenBuf[4] = { 0x55, 0x66, 0x77, 0x88 };
const unsigned char zeroLenExpected[4] = { 0x55, 0x66, 0x77, 0x88 };
unsigned char* zeroLenCallerOut = zeroLenBuf;
unsigned char* successOut = NULL;
X509* cert = NULL;
word32 origLen = 0;
int ret = 0;

ExpectNotNull(d2i_X509(&cert, &cert_buf, sizeof_server_cert_der_2048));
ExpectNotNull(cert);
ExpectNotNull(cert->derCert);
ExpectNotNull(cert->derCert->buffer);

if (EXPECT_SUCCESS()) {
origLen = cert->derCert->length;
cert->derCert->length = ((word32)INT_MAX) + 1U;
ret = i2d_X509(cert, &overflowOut);
cert->derCert->length = origLen;
ExpectIntEQ(ret, MEMORY_E);
ExpectNull(overflowOut);

cert->derCert->length = ((word32)INT_MAX) + 1U;
ret = i2d_X509(cert, &overflowCallerOut);
cert->derCert->length = origLen;
ExpectIntEQ(ret, MEMORY_E);
ExpectPtrEq(overflowCallerOut, overflowBuf);
ExpectIntEQ(XMEMCMP(overflowBuf, overflowExpected,
sizeof(overflowBuf)), 0);

cert->derCert->length = 0;
ret = i2d_X509(cert, &zeroLenOut);
cert->derCert->length = origLen;
ExpectIntEQ(ret, MEMORY_E);
ExpectNull(zeroLenOut);

cert->derCert->length = 0;
ret = i2d_X509(cert, &zeroLenCallerOut);
cert->derCert->length = origLen;
ExpectIntEQ(ret, MEMORY_E);
ExpectPtrEq(zeroLenCallerOut, zeroLenBuf);
ExpectIntEQ(XMEMCMP(zeroLenBuf, zeroLenExpected,
sizeof(zeroLenBuf)), 0);

ExpectIntGT(i2d_X509(cert, &successOut), 0);
ExpectNotNull(successOut);
}

XFREE(overflowOut, NULL, DYNAMIC_TYPE_OPENSSL);
XFREE(zeroLenOut, NULL, DYNAMIC_TYPE_OPENSSL);
XFREE(successOut, NULL, DYNAMIC_TYPE_OPENSSL);
X509_free(cert);
#endif
return EXPECT_RESULT();
}

int test_wolfSSL_PEM_read_X509(void)
{
EXPECT_DECLS;
Expand Down Expand Up @@ -244,4 +356,3 @@ int test_wolfSSL_PEM_write_bio_X509(void)
#endif
return EXPECT_RESULT();
}

6 changes: 6 additions & 0 deletions tests/api/test_ossl_x509_io.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,17 @@
#include <tests/api/api_decl.h>

int test_wolfSSL_i2d_X509(void);
int test_wolfSSL_X509_get_der_length_guards(void);
int test_wolfSSL_i2d_X509_der_length_guards(void);
int test_wolfSSL_PEM_read_X509(void);
int test_wolfSSL_PEM_write_bio_X509(void);

#define TEST_OSSL_X509_IO_DECLS \
TEST_DECL_GROUP("ossl_x509_io", test_wolfSSL_i2d_X509), \
TEST_DECL_GROUP("ossl_x509_io", \
test_wolfSSL_X509_get_der_length_guards), \
TEST_DECL_GROUP("ossl_x509_io", \
test_wolfSSL_i2d_X509_der_length_guards), \
TEST_DECL_GROUP("ossl_x509_io", test_wolfSSL_PEM_read_X509), \
TEST_DECL_GROUP("ossl_x509_io", test_wolfSSL_PEM_write_bio_X509)

Expand Down
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