Merge pull request #21922 from medhefgo/boot-fix

boot: More BCD parser fixes

3 files changed, 37 insertions, 19 deletions

diff --git a/src/boot/efi/bcd.c b/src/boot/efi/bcd.c
index 44c544f8f7..3eaabdd538 100644
--- a/src/boot/efi/bcd.c
+++ b/src/boot/efi/bcd.c
@@ -112,20 +112,30 @@ assert_cc(offsetof(KeyValue, data_offset) == 8);
 assert_cc(offsetof(KeyValue, data_type) == 12);
 assert_cc(offsetof(KeyValue, name) == 20);
 
+#define BAD_OFFSET(offset, len, max) \
+        ((UINT64) (offset) + (len) >= (max))
+
+#define BAD_STRUCT(type, offset, max) \
+        ((UINT64) (offset) + sizeof(type) >= (max))
+
+#define BAD_ARRAY(type, array, offset, array_len, max) \
+        ((UINT64) (offset) + offsetof(type, array) + \
+         sizeof((type){}.array[0]) * (UINT64) (array_len) >= (max))
+
 static const Key *get_key(const UINT8 *bcd, UINT32 bcd_len, UINT32 offset, const CHAR8 *name);
 
 static const Key *get_subkey(const UINT8 *bcd, UINT32 bcd_len, UINT32 offset, const CHAR8 *name) {
         assert(bcd);
         assert(name);
 
-        if ((UINT64) offset + sizeof(SubkeyFast) >= bcd_len)
+        if (BAD_STRUCT(SubkeyFast, offset, bcd_len))
                 return NULL;
 
         const SubkeyFast *subkey = (const SubkeyFast *) (bcd + offset);
         if (subkey->sig != SIG_SUBKEY_FAST)
                 return NULL;
 
-        if ((UINT64) offset + offsetof(SubkeyFast, entries) + sizeof(struct SubkeyFastEntry[subkey->n_entries]) >= bcd_len)
+        if (BAD_ARRAY(SubkeyFast, entries, offset, subkey->n_entries, bcd_len))
                 return NULL;
 
         for (UINT16 i = 0; i < subkey->n_entries; i++) {
@@ -147,14 +157,14 @@ static const Key *get_key(const UINT8 *bcd, UINT32 bcd_len, UINT32 offset, const
         assert(bcd);
         assert(name);
 
-        if ((UINT64) offset + sizeof(Key) >= bcd_len)
+        if (BAD_STRUCT(Key, offset, bcd_len))
                 return NULL;
 
         const Key *key = (const Key *) (bcd + offset);
         if (key->sig != SIG_KEY)
                 return NULL;
 
-        if ((UINT64) offset + offsetof(Key, key_name) + sizeof(CHAR8[key->key_name_len]) >= bcd_len)
+        if (BAD_ARRAY(Key, key_name, offset, key->key_name_len, bcd_len))
                 return NULL;
 
         if (*name) {
@@ -176,21 +186,22 @@ static const KeyValue *get_key_value(const UINT8 *bcd, UINT32 bcd_len, const Key
         if (key->n_key_values == 0)
                 return NULL;
 
-        if ((UINT64) key->key_values_offset + sizeof(UINT32[key->n_key_values]) >= bcd_len)
+        if (BAD_OFFSET(key->key_values_offset, sizeof(UINT32) * (UINT64) key->n_key_values, bcd_len) ||
+            (UINTN)(bcd + key->key_values_offset) % sizeof(UINT32) != 0)
                 return NULL;
 
         const UINT32 *key_value_list = (const UINT32 *) (bcd + key->key_values_offset);
         for (UINT32 i = 0; i < key->n_key_values; i++) {
                 UINT32 offset = *(key_value_list + i);
 
-                if ((UINT64) offset + sizeof(KeyValue) >= bcd_len)
+                if (BAD_STRUCT(KeyValue, offset, bcd_len))
                         continue;
 
                 const KeyValue *kv = (const KeyValue *) (bcd + offset);
                 if (kv->sig != SIG_KEY_VALUE)
                         continue;
 
-                if ((UINT64) offset + offsetof(KeyValue, name) + kv->name_len >= bcd_len)
+                if (BAD_ARRAY(KeyValue, name, offset, kv->name_len, bcd_len))
                         continue;
 
                 /* If most significant bit is set, data is stored in data_offset itself, but
@@ -199,7 +210,7 @@ static const KeyValue *get_key_value(const UINT8 *bcd, UINT32 bcd_len, const Key
                 if (FLAGS_SET(kv->data_size, UINT32_C(1) << 31))
                         continue;
 
-                if ((UINT64) kv->data_offset + kv->data_size >= bcd_len)
+                if (BAD_OFFSET(kv->data_offset, kv->data_size, bcd_len))
                         continue;
 
                 if (strncaseeqa(name, kv->name, kv->name_len) && strlena(name) == kv->name_len)
@@ -266,7 +277,8 @@ TEST_STATIC CHAR16 *get_bcd_title(UINT8 *bcd, UINTN bcd_len) {
 
         CHAR8 order_guid[sizeof("{00000000-0000-0000-0000-000000000000}\0")];
         if (displayorder_value->data_type != REG_MULTI_SZ ||
-            displayorder_value->data_size != sizeof(CHAR16) * sizeof(order_guid))
+            displayorder_value->data_size != sizeof(CHAR16[sizeof(order_guid)]) ||
+            (UINTN)(bcd + displayorder_value->data_offset) % sizeof(CHAR16) != 0)
                 /* BCD is multi-boot. */
                 return NULL;
 
@@ -312,7 +324,8 @@ TEST_STATIC CHAR16 *get_bcd_title(UINT8 *bcd, UINTN bcd_len) {
 
         if (description_value->data_type != REG_SZ ||
             description_value->data_size < sizeof(CHAR16) ||
-            description_value->data_size % sizeof(CHAR16) != 0)
+            description_value->data_size % sizeof(CHAR16) != 0 ||
+            (UINTN)(bcd + description_value->data_offset) % sizeof(CHAR16))
                 return NULL;
 
         /* The data should already be NUL-terminated. */
diff --git a/src/boot/efi/boot.c b/src/boot/efi/boot.c
index 17d14a5dac..0360d2a0bf 100644
--- a/src/boot/efi/boot.c
+++ b/src/boot/efi/boot.c
@@ -1941,6 +1941,7 @@ static void config_entry_add_osx(Config *config) {
 }
 
 static void config_entry_add_windows(Config *config, EFI_HANDLE *device, EFI_FILE *root_dir) {
+#if defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__)
         _cleanup_freepool_ CHAR8 *bcd = NULL;
         CHAR16 *title = NULL;
         EFI_STATUS err;
@@ -1961,6 +1962,7 @@ static void config_entry_add_windows(Config *config, EFI_HANDLE *device, EFI_FIL
         config_entry_add_loader_auto(config, device, root_dir, NULL,
                                      L"auto-windows", 'w', title ?: L"Windows Boot Manager",
                                      L"\\EFI\\Microsoft\\Boot\\bootmgfw.efi");
+#endif
 }
 
 static void config_entry_add_linux(
diff --git a/src/boot/efi/meson.build b/src/boot/efi/meson.build
index a6a0fa2595..03e603a376 100644
--- a/src/boot/efi/meson.build
+++ b/src/boot/efi/meson.build
@@ -331,7 +331,6 @@ common_sources = [
         'util.c']
 
 systemd_boot_sources = [
-        'bcd.c',
         'boot.c',
         'console.c',
         'drivers.c',
@@ -351,6 +350,18 @@ else
         stub_sources += 'linux.c'
 endif
 
+# BCD parser only makes sense on arches that Windows supports.
+if efi_arch[1] in ['ia32', 'x86_64', 'arm', 'aarch64']
+        systemd_boot_sources += 'bcd.c'
+        tests += [
+                [['src/boot/efi/test-bcd.c'],
+                 [],
+                 [libzstd],
+                 [],
+                 'HAVE_ZSTD'],
+        ]
+endif
+
 systemd_boot_objects = []
 stub_objects = []
 foreach file : fundamental_source_paths + common_sources + systemd_boot_sources + stub_sources
@@ -407,14 +418,6 @@ endforeach
 
 ############################################################
 
-tests += [
-        [['src/boot/efi/test-bcd.c'],
-         [],
-         [libzstd],
-         [],
-         'HAVE_ZSTD'],
-]
-
 test_efi_disk_img = custom_target(
         'test-efi-disk.img',
         input : [efi_stubs[0][0], efi_stubs[1][1]],