x11-misc/alock/files/check-setuid.patch

--- a/src/auth_pam.c
+++ b/src/auth_pam.c
@@ -138,7 +138,12 @@
 
     /* we can be installed setuid root to support shadow passwords,
        and we don't need root privileges any longer.  --marekm */
-    setuid(getuid());
+    int retval;
+    retval = setuid(getuid());
+    /* if setuid's return value isn't checked, it's a security issue */
+    if (retval != 0) {
+        return 0;
+    }
 
     return 1;
 }
--- a/src/auth_passwd.c
+++ a/src/auth_passwd.c
@@ -68,7 +68,11 @@
 
     /* we can be installed setuid root to support shadow passwords,
        and we don't need root privileges any longer.  --marekm */
-    setuid(getuid());
+    int retval;
+    retval = setuid(getuid());
+    if (retval != 0) {
+        return 0;
+    }
 
     if (strlen(pwd_entry->pw_passwd) < 13) {
         perror("password entry has no pwd\n");