lib/x509: Avoid memcpy when string is empty

This fixes an ASAN warning in fuzz/gnutls_private_key_parser_fuzzer
when run against the malformed private key
fuzz/gnutls_private_key_parser_fuzzer.in/10a5c92fa30ddb6cbb4286d7699b2b7a7e032b17

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>

diff --git a/lib/x509/common.c b/lib/x509/common.c
index c156bd96a9e1d36acb93367441b4a44150509d3e..94d206ff758481fb1a59a8215bce9e3640b1c0b1 100644 (file)
--- a/lib/x509/common.c
+++ b/lib/x509/common.c
@@ -630,7 +630,8 @@ _gnutls_x509_decode_string(unsigned int etype,
        if (td.data == NULL)
                return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
 
-       memcpy(td.data, str, str_size);
+        if (str_size > 0)
+                memcpy(td.data, str, str_size);
        td.data[str_size] = 0;
 
        if (allow_ber)