From 68d7c268f8b0e28ae719a8c783e3ded253563f9d Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 22 Oct 2018 19:59:45 +0200
Subject: [PATCH] efivars: let's add some validation of boot menu entry name
 syntax

---
 src/shared/efivars.c | 21 +++++++++++++++++----
 src/shared/efivars.h |  2 ++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/shared/efivars.c b/src/shared/efivars.c
index 360ef03400..fbed9027c1 100644
--- a/src/shared/efivars.c
+++ b/src/shared/efivars.c
@@ -771,6 +771,16 @@ int efi_loader_get_device_part_uuid(sd_id128_t *u) {
         return 0;
 }
 
+bool efi_loader_entry_name_valid(const char *s) {
+        if (isempty(s))
+                return false;
+
+        if (strlen(s) > FILENAME_MAX) /* Make sure entry names fit in filenames */
+                return false;
+
+        return in_charset(s, ALPHANUMERICAL "-");
+}
+
 int efi_loader_get_entries(char ***ret) {
         _cleanup_free_ char16_t *entries = NULL;
         _cleanup_strv_free_ char **l = NULL;
@@ -789,7 +799,7 @@ int efi_loader_get_entries(char ***ret) {
         /* The variable contains a series of individually NUL terminated UTF-16 strings. */
 
         for (i = 0, start = 0;; i++) {
-                char *decoded;
+                _cleanup_free_ char *decoded = NULL;
                 bool end;
 
                 /* Is this the end of the variable's data? */
@@ -805,9 +815,12 @@ int efi_loader_get_entries(char ***ret) {
                 if (!decoded)
                         return -ENOMEM;
 
-                r = strv_consume(&l, decoded);
-                if (r < 0)
-                        return r;
+                if (efi_loader_entry_name_valid(decoded)) {
+                        r = strv_consume(&l, TAKE_PTR(decoded));
+                        if (r < 0)
+                                return r;
+                } else
+                        log_debug("Ignoring invalid loader entry '%s'.", decoded);
 
                 /* We reached the end of the variable */
                 if (end)
diff --git a/src/shared/efivars.h b/src/shared/efivars.h
index 51ecf6a279..92670c82c7 100644
--- a/src/shared/efivars.h
+++ b/src/shared/efivars.h
@@ -50,6 +50,8 @@ int efi_loader_get_boot_usec(usec_t *firmware, usec_t *loader);
 
 int efi_loader_get_entries(char ***ret);
 
+bool efi_loader_entry_name_valid(const char *s);
+
 int efi_loader_get_features(uint64_t *ret);
 
 #else