in xe_new change casting to be more narrowly tailored; and replace malloc usage which failed to check for NULL with an automatic buffer

1 files changed, 17 insertions, 13 deletions

diff --git a/src/openssl.c b/src/openssl.c
index 7bd9c61..0701642 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -1829,15 +1829,15 @@ static int xe_new(lua_State *L) {
 
         X509_EXTENSION **ud = prepsimple(L, X509_EXT_CLASS);
 
-        char *name = (char *) luaL_checkstring(L, 1);
-        char *value = (char *) luaL_checkstring(L, 2);
+        const char *name = luaL_checkstring(L, 1);
+        const char *value = luaL_checkstring(L, 2);
 
         CONF *conf = NULL;
-        X509V3_CTX *ctx = NULL;
+        X509V3_CTX cbuf = { 0 }, *ctx = NULL;
         X509_EXTENSION *ext = NULL;
 
         if (!lua_isnil(L, 3)) {
-                char *cdata = (char *) luaL_checkstring(L, 3);
+                const char *cdata = luaL_checkstring(L, 3);
                 BIO *bio = getbio(L);
                 if (BIO_puts(bio, cdata) < 0)
                         goto error;
@@ -1847,23 +1847,27 @@ static int xe_new(lua_State *L) {
                 if (!NCONF_load_bio(conf, bio, NULL))
                         goto error;
 
-                ctx = (X509V3_CTX *) malloc(sizeof (X509V3_CTX));
+                ctx = &cbuf;
                 X509V3_set_nconf(ctx, conf);
         }
 
-        if (!(*ud = X509V3_EXT_nconf(conf, ctx, name, value)))
+        /*
+         * NOTE: AFAICT neither name nor value are modified. The API just
+         * doesn't have the proper const-qualifiers. See
+         * crypto/x509v3/v3_conf.c in OpenSSL.
+         *
+         * Also seems to be okay to pass NULL conf. Both NCONF_get_section
+         * and sk_CONF_VALUE_num can handle NULL arguments. See do_ext_nconf
+         * in v3_conf.c.
+         */
+        if (!(*ud = X509V3_EXT_nconf(conf, ctx, (char *)name, (char *)value)))
                 goto error;
 
-        if (conf) {
-                free(ctx);
+        if (conf)
                 NCONF_free(conf);
-        }
 
         return 1;
-
-        error:
-        if (ctx)
-                free(ctx);
+error:
         if (conf)
                 NCONF_free(conf);