initrd: fix crash parsing empty rd.znet argumentbg/initrd-znet-empty

Ignore a rd.znet argument without subchannels. When using net.ifnames
(the default), subchannels are used to build the interface name, which
is required to match the right connection.

With net.ifnames=0 the interface name is build using a prefix and a
global counter and therefore in theory it is possible to omit
subchannels. However, without subchannels there won't be a udev rule
that renames the interface and so it can't work.

https://bugzilla.redhat.com/show_bug.cgi?id=1931284
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/783

2 files changed, 24 insertions, 0 deletions

diff --git a/src/nm-initrd-generator/nmi-cmdline-reader.c b/src/nm-initrd-generator/nmi-cmdline-reader.c
index d6b84c2e57..37f3f51c3d 100644
--- a/src/nm-initrd-generator/nmi-cmdline-reader.c
+++ b/src/nm-initrd-generator/nmi-cmdline-reader.c
@@ -924,6 +924,11 @@ reader_parse_rd_znet(Reader *reader, char *argument, gboolean net_ifnames)
     subchannels[0] = get_word(&argument, ',');
     subchannels[1] = get_word(&argument, ',');
 
+    /* Without subchannels we can't univocally match
+     * a device. */
+    if (!subchannels[0] || !subchannels[1])
+        return;
+
     if (nm_streq0(nettype, "ctc")) {
         if (net_ifnames == TRUE) {
             prefix = "sl";
diff --git a/src/nm-initrd-generator/tests/test-cmdline-reader.c b/src/nm-initrd-generator/tests/test-cmdline-reader.c
index 0bdd430b22..9292c44114 100644
--- a/src/nm-initrd-generator/tests/test-cmdline-reader.c
+++ b/src/nm-initrd-generator/tests/test-cmdline-reader.c
@@ -1855,6 +1855,24 @@ test_rd_znet_no_ip(void)
 }
 
 static void
+test_rd_znet_malformed(void)
+{
+    const char *const *const ARGV0  = NM_MAKE_STRV("rd.znet=");
+    const char *const *const ARGV1  = NM_MAKE_STRV("rd.znet=,");
+    const char *const *const ARGV2  = NM_MAKE_STRV("rd.znet=foobar");
+    const char *const *const ARGV3  = NM_MAKE_STRV("rd.znet=qeth,0.0.0800,,,layer2=0,portno=1");
+    const char *const *const ARGV[] = {ARGV0, ARGV1, ARGV2, ARGV3};
+    guint                    i;
+
+    for (i = 0; i < G_N_ELEMENTS(ARGV); i++) {
+        gs_unref_hashtable GHashTable *connections = NULL;
+
+        connections = _parse_cons(ARGV[i]);
+        g_assert_cmpint(g_hash_table_size(connections), ==, 0);
+    }
+}
+
+static void
 test_bootif_ip(void)
 {
     const char *const *ARGV                  = NM_MAKE_STRV("BOOTIF=00:53:AB:cd:02:03", "ip=dhcp");
@@ -2189,6 +2207,7 @@ main(int argc, char **argv)
     g_test_add_func("/initrd/cmdline/rd_znet", test_rd_znet);
     g_test_add_func("/initrd/cmdline/rd_znet/legacy", test_rd_znet_legacy);
     g_test_add_func("/initrd/cmdline/rd_znet/no_ip", test_rd_znet_no_ip);
+    g_test_add_func("/initrd/cmdline/rd_znet/empty", test_rd_znet_malformed);
     g_test_add_func("/initrd/cmdline/bootif/ip", test_bootif_ip);
     g_test_add_func("/initrd/cmdline/bootif/no_ip", test_bootif_no_ip);
     g_test_add_func("/initrd/cmdline/bootif/hwtype", test_bootif_hwtype);