sd-device: refuse earlier when too long ifname is passed to sd_device_new_from_ifname()

Otherwise, alloca() called in strjoina() may trigger assertion.

This partially reverts 3652891c3904992e21739e9bfb004073841db63c.
The commit mistakenly dropped the check.

diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index dafda626f077d0b15d8778139aa76da017b0e4aa..3d683fb280269e9499d189550b941219f3629b61 100644 (file)
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -345,9 +345,11 @@ _public_ int sd_device_new_from_ifname(sd_device **ret, const char *ifname) {
         assert_return(ret, -EINVAL);
         assert_return(ifname, -EINVAL);
 
-        r = device_new_from_main_ifname(ret, ifname);
-        if (r >= 0)
-                return r;
+        if (ifname_valid(ifname)) {
+                r = device_new_from_main_ifname(ret, ifname);
+                if (r >= 0)
+                        return r;
+        }
 
         r = rtnl_resolve_ifname_full(NULL, RESOLVE_IFNAME_ALTERNATIVE | RESOLVE_IFNAME_NUMERIC, ifname, &main_name, NULL);
         if (r < 0)