zdev: Harden against invalid hypervisor data

Reduce chances of unintended side-effects when evaluating hypervisor
data which might have been corrupted.

Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/dracut/95zdev/parse-zdev.sh

@@ -41,9 +41,19 @@ if [ $zdev_auto -eq 1 ] ; then
     chzdev --import "$zdev_fw_file" $zdev_base_args
 
     # Get information about DPM environment
-    for line in $($zdev_id) ; do
-        eval "$line"
-    done
+    tmp="/tmp/zdev_id.env"
+    if "$zdev_id" >"$tmp"; then
+        while IFS='=' read -r key val; do
+            case "$key" in
+            ZDEV_*)
+                val=${val#\"}
+                val=${val%\"}
+                export "$key=$val"
+                ;;
+            esac
+        done <"$tmp"
+    fi
+    rm -f "$tmp"
 
     if [ "$ZDEV_IS_DPM,$ZDEV_NEST_LEVEL,$ZDEV_HYPERVISOR_0" = "1,1,LPAR" ] ; then
       # Manually iterate over existing PCI devices - there is a udev rule

zdev/include/sanitize.h

@@ -0,0 +1,32 @@
+/*
+ * zdev - Modify and display the persistent configuration of devices
+ *
+ * Copyright IBM Corp. 2026
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef SANITIZE_H
+#define SANITIZE_H
+
+#include <ctype.h>
+#include <string.h>
+
+/* Valid control-program identifier special characters */
+#define VALID_CPNAME	"/"
+
+static inline int is_safe_char(unsigned char c, const char *set)
+{
+	return isalnum(c) || strchr(set, c);
+}
+
+static inline void sanitize(char *s, const char *set)
+{
+	for (; *s; s++) {
+		if (!is_safe_char((unsigned char)*s, set))
+			*s = '_';
+	}
+}
+
+#endif /* SANITIZE_H */

zdev/src/zdev_id.c

@@ -13,6 +13,7 @@
 #include <string.h>
 #include <ctype.h>
 
+#include "sanitize.h"
 #include "zdev.h"
 #include "zdev_id.h"
 
@@ -69,6 +70,7 @@ static void process_sysinfo(const char *filename)
 			free(substr);
 		} else if (sscanf(line, "VM%*d Control Program: %ms ",
 				  &substr) == 1) {
+			sanitize(substr, VALID_CPNAME);
 			array_add(&cps, &num_cps, substr);
 			free(substr);
 		}