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X.509: Remove red'n bounds checks and zeroiz'n in OtherName parsing

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- ASN.1 parsing functions check that length don't exceed buffer bounds,
  so checks `p + len > end` are redundant.
- If `p + len == end`, this is erroneous because we expect further fields,
  which is automatically caught by the next ASN.1 parsing call.

Hence, the two branches handling `p + len >= end` in x509_get_other_name()
can be removed.

Further, zeroization of the `other_name` structure isn't necessary
because it's not confidential (and it's also not performed on other
error conditions in this function).
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
This commit is contained in:
hanno-becker 2023-02-08 08:50:01 -05:00 committed by Andrzej Kurek
parent 75ab076971
commit c4f885dc02
1 changed files with 10 additions and 12 deletions
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22
library/x509_crt.c
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@ -1742,11 +1742,6 @@ static int x509_get_other_name(const mbedtls_x509_buf *subject_alt_name,
return MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE;
}
if (p + len >= end) {
mbedtls_platform_zeroize(other_name, sizeof(*other_name));
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}
p += len;
if ((ret = mbedtls_asn1_get_tag(&p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC)) !=
@ -1754,11 +1749,21 @@ static int x509_get_other_name(const mbedtls_x509_buf *subject_alt_name,
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
if (end != p + len) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}
if ((ret = mbedtls_asn1_get_tag(&p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
if (end != p + len) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}
if ((ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OID)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret);
}
@ -1767,11 +1772,6 @@ static int x509_get_other_name(const mbedtls_x509_buf *subject_alt_name,
other_name->value.hardware_module_name.oid.p = p;
other_name->value.hardware_module_name.oid.len = len;
if (p + len >= end) {
mbedtls_platform_zeroize(other_name, sizeof(*other_name));
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}
p += len;
if ((ret = mbedtls_asn1_get_tag(&p, end, &len,
MBEDTLS_ASN1_OCTET_STRING)) != 0) {
@ -1783,8 +1783,6 @@ static int x509_get_other_name(const mbedtls_x509_buf *subject_alt_name,
other_name->value.hardware_module_name.val.len = len;
p += len;
if (p != end) {
mbedtls_platform_zeroize(other_name,
sizeof(*other_name));
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
}