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Improve mbedtls_asn1_write_int to support values >255

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mbedtls_asn1_write_int had an undocumented restriction to values that
fit in a single octet. Fix this.

Negative integers are still not supported.
This commit is contained in:
Gilles Peskine 2019-03-01 18:15:18 +01:00
parent 3a032c36c1
commit 1dbab67ce8
1 changed files with 10 additions and 7 deletions
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17
library/asn1write.c
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@ -236,17 +236,20 @@ int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
int ret; int ret;
size_t len = 0; size_t len = 0;
if( *p - start < 1 ) do
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
len += 1;
*--(*p) = val;
if( val > 0 && **p & 0x80 )
{ {
if( *p - start < 1 ) if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
len += 1;
*--(*p) = val & 0xff;
val >>= 8;
}
while( val > 0 );
if( **p & 0x80 )
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = 0x00; *--(*p) = 0x00;
len += 1; len += 1;
} }