Avoid use of large stack buffers in mbedtls_x509_write_crt_pem()
This commit rewrites mbedtls_x509write_crt_pem() to not use
a statically size stack buffer to temporarily store the DER
encoded form of the certificate to be written.
This is not necessary because the DER-to-PEM conversion
accepts overlapping input and output buffers.
@@ -527,18 +527,17 @@ int mbedtls_x509write_crt_pem( mbedtls_x509write_cert *crt,
void *p_rng )
{
int ret;
- unsigned char output_buf[4096];
- size_t olen = 0;
+ size_t olen;
- if( ( ret = mbedtls_x509write_crt_der( crt, output_buf, sizeof(output_buf),
+ if( ( ret = mbedtls_x509write_crt_der( crt, buf, size,
f_rng, p_rng ) ) < 0 )
{
return( ret );
}
if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CRT, PEM_END_CRT,
- output_buf + sizeof(output_buf) - ret,
- ret, buf, size, &olen ) ) != 0 )
+ buf + size - ret, ret,
+ buf, size, &olen ) ) != 0 )
{
return( ret );
}
