Fix signature algorithms list entry getting overwritten by length.
Fix bug whereby the supported signature algorithm list sent by the
server in the certificate request would not leave enough space for the
length to be written, and thus the first element would get overwritten,
leaving two random bytes in the last entry.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/library/ssl_tls12_server.c b/library/ssl_tls12_server.c
index 71f703c..3dab246 100644
--- a/library/ssl_tls12_server.c
+++ b/library/ssl_tls12_server.c
@@ -2531,10 +2531,15 @@
if( ! mbedtls_ssl_sig_alg_is_supported( ssl, *sig_alg ) )
continue;
- MBEDTLS_PUT_UINT16_BE( *sig_alg, p, sa_len );
+ /* Write elements at offsets starting from 1 (offset 0 is for the
+ * length). Thus the offset of each element is the length of the
+ * partial list including that element. */
sa_len += 2;
+ MBEDTLS_PUT_UINT16_BE( *sig_alg, p, sa_len );
+
}
+ /* Fill in list length. */
MBEDTLS_PUT_UINT16_BE( sa_len, p, 0 );
sa_len += 2;
p += sa_len;