Fix too early argv freeing when registering DNS

When registering DNS on Windows, argv is freed after being used in first
ipconfig command (/flushdns).

Then same argv is used uninitialized in next ipconfig command
(/registerdns)
causing heap exception and subprocess crash.

As a consequence second command is never executed and locked netcmd
semaphore is not cleanly released.

Removing argv freeing between ipconfig calls solves the problem.

This issue was introduced in commit 870e240 (argv: do fewer memory
re-allocations). After a quick glance at commit no similar problem was
spotted in rest of the argv related changes.

Signed-off-by: Domagoj Pensa <domagoj@pensa.hr>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20201215171600.25534-1-domagoj@pensa.hr>
URL: https://www.mail-archive.com/search?l=mid&q=20201215171600.25534-1-domagoj@pensa.hr
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit ab4688e3bd78d010ccc96adec66ab552bd009328)

diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 8315a42644660fecf4011a292e7a44071a11bd34..eff4bd0997deac5d13bcbdfb661626854f0cfa69 100644 (file)
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -5240,7 +5240,6 @@ ipconfig_register_dns(const struct env_set *es)
                 WIN_IPCONFIG_PATH_SUFFIX);
     argv_msg(D_TUNTAP_INFO, &argv);
     openvpn_execve_check(&argv, es, 0, err);
-    argv_free(&argv);
 
     argv_printf(&argv, "%s%s /registerdns",
                 get_win_sys_path(),