From: Roy Marples <roy@marples.name>
Date: Sat, 20 Jun 2026 22:00:57 +0000 (+0100)
Subject: udev: Ensure we have a subsystem, action and ifname
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=69f107577daf6bddbcf8e1a3384935cf567e623f;p=thirdparty%2Fdhcpcd.git

udev: Ensure we have a subsystem, action and ifname

As udev could return NULL for them.

Reported by NVIDIA Project Vanessa
---

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 84a4015d..c8ce6aa2 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -35,6 +35,9 @@ jobs:
         os: [ ubuntu-latest, ubuntu-22.04 ]
     runs-on: ${{ matrix.os }}
 
+    - name: Install libudev-dev
+      run: sudo apt install -y pkg-config libudev-dev
+
     steps:
     - uses: actions/checkout@v6
     
diff --git a/src/dev/udev.c b/src/dev/udev.c
index 5a6735b5..0e43b169 100644
--- a/src/dev/udev.c
+++ b/src/dev/udev.c
@@ -90,9 +90,12 @@ udev_handle_device(void *ctx)
 	action = udev_device_get_action(device);
 
 	/* udev filter documentation says "usually" so double check */
-	if (strcmp(subsystem, "net") == 0) {
+	if (subsystem != NULL && strcmp(subsystem, "net") == 0) {
 		logdebugx("%s: libudev: %s", ifname, action);
-		if (strcmp(action, "add") == 0 || strcmp(action, "move") == 0)
+		if (action == NULL || ifname == NULL)
+			;
+		else if (strcmp(action, "add") == 0 ||
+		    strcmp(action, "move") == 0)
 			dhcpcd.handle_interface(ctx, 1, ifname);
 		else if (strcmp(action, "remove") == 0)
 			dhcpcd.handle_interface(ctx, -1, ifname);