cron2 has submitted this change. (
http://gerrit.openvpn.net/c/openvpn/+/1418?usp=email )
Change subject: Prevent crash on invalid server-ipv6 argument
......................................................................
Prevent crash on invalid server-ipv6 argument
`get_addr_generic()` expects `openvpn_getaddrinfo()` to return a newly
allocated struct, but getaddrinfo(3) failure leaves `*ai = NULL` as-is.
On OpenBSD, unlike free(3), freegetaddrinfo(3) requires a valid struct,
thus callers must check the argument to avoid NULL-deref or double-free:
```
$ openvpn --server-ipv6 ''
2025-12-06 11:59:18 RESOLVE: Cannot resolve host address: :[AF_INET6] (no
address associated with name)
Segmentation fault (core dumped)
```
Guard against empty `ai`, i.e. failure, like similar code already does:
```
$ ./openvpn --server-ipv6 ''
2025-12-06 12:05:11 RESOLVE: Cannot resolve host address: :[AF_INET6] (no
address associated with name)
Options error: error parsing --server-ipv6 parameter
Use --help for more information.
```
Spotted through a configuration typo "server-ipv6 fd00:/64" with 2.6.17,
reproduced with and tested against 2.7rc3 on OpenBSD/amd64 7.8-current.
NB: Standards are unclear wrt. freeaddrinfo(3)'s NULL handling;
Linux, FreeBSD and illumos do check it and thus not crash.
Github: fixes OpenVPN/openvpn#930
Change-Id: I99a6604fdfc682f9609bfe7672aa78285084dcb9
Signed-off-by: Klemens Nanni <[email protected]>
Acked-by: Gert Doering <[email protected]>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1418
Message-Id: <[email protected]>
URL:
https://www.mail-archive.com/[email protected]/msg34870.html
Signed-off-by: Gert Doering <[email protected]>
---
M src/openvpn/socket.c
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index 46bedf4..80c2895 100644
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -189,7 +189,10 @@
*sep = '/';
}
out:
- freeaddrinfo(ai);
+ if (ai)
+ {
+ freeaddrinfo(ai);
+ }
free(var_host);
return ret;
--
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Gerrit-MessageType: merged
Gerrit-Project: openvpn
Gerrit-Branch: master
Gerrit-Change-Id: I99a6604fdfc682f9609bfe7672aa78285084dcb9
Gerrit-Change-Number: 1418
Gerrit-PatchSet: 3
Gerrit-Owner: klemens <[email protected]>
Gerrit-Reviewer: cron2 <[email protected]>
Gerrit-Reviewer: plaisthos <[email protected]>
Gerrit-CC: openvpn-devel <[email protected]>
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