diff options
Diffstat (limited to 'thirdparty/mbedtls/library/asn1write.c')
| -rw-r--r-- | thirdparty/mbedtls/library/asn1write.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/thirdparty/mbedtls/library/asn1write.c b/thirdparty/mbedtls/library/asn1write.c index a4d23f6196..c0b4622d58 100644 --- a/thirdparty/mbedtls/library/asn1write.c +++ b/thirdparty/mbedtls/library/asn1write.c @@ -294,22 +294,28 @@ int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start, const unsigned char *buf, size_t bits ) { int ret; - size_t len = 0, size; + size_t len = 0; + size_t unused_bits, byte_len; - size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 ); + byte_len = ( bits + 7 ) / 8; + unused_bits = ( byte_len * 8 ) - bits; - // Calculate byte length - // - if( *p < start || (size_t)( *p - start ) < size + 1 ) + if( *p < start || (size_t)( *p - start ) < byte_len + 1 ) return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); - len = size + 1; - (*p) -= size; - memcpy( *p, buf, size ); + len = byte_len + 1; - // Write unused bits - // - *--(*p) = (unsigned char) (size * 8 - bits); + /* Write the bitstring. Ensure the unused bits are zeroed */ + if( byte_len > 0 ) + { + byte_len--; + *--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 ); + ( *p ) -= byte_len; + memcpy( *p, buf, byte_len ); + } + + /* Write unused bits */ + *--( *p ) = (unsigned char)unused_bits; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) ); |