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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
2019-09-13 14:19:03 +01:00
committed by Andrzej Kurek
parent 9de47b485b
commit c081e6b4c3
1 changed files with 0 additions and 14 deletions
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14
library/x509_crt.c
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@@ -1733,12 +1733,6 @@ static int x509_get_other_name( const mbedtls_x509_buf *subject_alt_name,
return( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE ); 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; p += len;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 ) MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 )
@@ -1755,12 +1749,6 @@ 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.p = p;
other_name->value.hardware_module_name.oid.len = len; 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; p += len;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_OCTET_STRING ) ) != 0 ) MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
@@ -1772,8 +1760,6 @@ static int x509_get_other_name( const mbedtls_x509_buf *subject_alt_name,
p += len; p += len;
if( p != end ) if( p != end )
{ {
mbedtls_platform_zeroize( other_name,
sizeof( *other_name ) );
return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) ); MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
} }