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[Openvpn-devel,v1] dco_linux: validate tun interface before fetching stats

Message ID 20250902150848.14160-1-gert@greenie.muc.de
State New
Headers show
Series [Openvpn-devel,v1] dco_linux: validate tun interface before fetching stats | expand

Commit Message

Gert Doering Sept. 2, 2025, 3:08 p.m. UTC 
From: Ralf Lici <ralf@mandelbit.com>

If dco_get_peer_stats() is called with an uninitialized c->c1.tuntap it
results in a segfault. This issue happens when a client who has not
connected to any server:
  - has --management and exits,
  - has --management and a management interface client issues either
    `bytecount` or `status` or
  - if SIGUSR2 is sent to it.

Add a check to ensure the tun interface was set up before attempting to
retrieve peer statistics.

Change-Id: I40c11864745cc1619cb9cbf490b168f90feb5eac
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1166
This mail reflects revision 1 of this Change.

Acked-by according to Gerrit (reflected above):
Gert Doering <gert@greenie.muc.de>
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Patch

diff --git a/src/openvpn/dco_linux.c b/src/openvpn/dco_linux.c
index a3907fe..6e629c1 100644
--- a/src/openvpn/dco_linux.c
+++ b/src/openvpn/dco_linux.c
@@ -1139,6 +1139,8 @@ 
 static int
 dco_get_peer(dco_context_t *dco, int peer_id, const bool raise_sigusr1_on_err)
 {
+    ASSERT(dco);
+
     /* peer_id == -1 means "dump all peers", but this is allowed in MP mode only.
      * If it happens in P2P mode it means that the DCO peer was deleted and we
      * can simply bail out
@@ -1182,6 +1184,11 @@ 
 int
 dco_get_peer_stats(struct context *c, const bool raise_sigusr1_on_err)
 {
+    if (!tuntap_defined(c->c1.tuntap))
+    {
+        return -1;
+    }
+
     return dco_get_peer(&c->c1.tuntap->dco, c->c2.tls_multi->dco_peer_id, raise_sigusr1_on_err);
 }