chid-fundamental: not all SMBIOS fields are available on all systems

And the CHID documentation says that CHIDs that require fields that are
not available on the local system should not be generated. Follow that,
and generate a NULL CHID in that case (which we generally ignore
otherwise).

diff --git a/src/fundamental/chid-fundamental.c b/src/fundamental/chid-fundamental.c
index 9c719a334dd426e8f266f78f9b6e1ec70940644a..ab366ca8ee4bca1c0b32a486e184bce86dedb501 100644 (file)
--- a/src/fundamental/chid-fundamental.c
+++ b/src/fundamental/chid-fundamental.c
@@ -28,7 +28,11 @@
 #include "memory-util-fundamental.h"
 #include "sha1-fundamental.h"
 
-static void get_chid(const char16_t *const smbios_fields[static _CHID_SMBIOS_FIELDS_MAX], uint32_t mask, EFI_GUID *ret_chid) {
+static void get_chid(
+                const char16_t *const smbios_fields[static _CHID_SMBIOS_FIELDS_MAX],
+                uint32_t mask,
+                EFI_GUID *ret_chid) {
+
         assert(mask != 0);
         assert(ret_chid);
         const EFI_GUID namespace = { UINT32_C(0x12d8ff70), UINT16_C(0x7f4c), UINT16_C(0x7d4c), {} }; /* Swapped to BE */
@@ -38,13 +42,22 @@ static void get_chid(const char16_t *const smbios_fields[static _CHID_SMBIOS_FIE
 
         sha1_process_bytes(&namespace, sizeof(namespace), &ctx);
 
-        for (unsigned i = 0; i < _CHID_SMBIOS_FIELDS_MAX; i++)
-                if ((mask >> i) & 1) {
-                        if (i > 0)
-                                sha1_process_bytes(L"&", 2, &ctx);
-                        sha1_process_bytes(smbios_fields[i], strlen16(smbios_fields[i]) * sizeof(char16_t), &ctx);
+        for (unsigned i = 0; i < _CHID_SMBIOS_FIELDS_MAX; i++) {
+                if (!((mask >> i) & 1))
+                        continue;
+
+                if (!smbios_fields[i]) {
+                        /* If some SMBIOS field is missing, don't generate the CHID, as per spec */
+                        memzero(ret_chid, sizeof(EFI_GUID));
+                        return;
                 }
 
+                if (i > 0)
+                        sha1_process_bytes(L"&", 2, &ctx);
+
+                sha1_process_bytes(smbios_fields[i], strlen16(smbios_fields[i]) * sizeof(char16_t), &ctx);
+        }
+
         uint8_t hash[SHA1_DIGEST_SIZE];
         sha1_finish_ctx(&ctx, hash);
 
@@ -111,9 +124,12 @@ void chid_calculate(const char16_t *const smbios_fields[static _CHID_SMBIOS_FIEL
         assert(smbios_fields);
         assert(ret_chids);
 
-        for (size_t i = 0; i < CHID_TYPES_MAX; i++)
-                if (chid_smbios_table[i] != 0)
-                        get_chid(smbios_fields, chid_smbios_table[i], &ret_chids[i]);
-                else
+        for (size_t i = 0; i < CHID_TYPES_MAX; i++) {
+                if (chid_smbios_table[i] == 0) {
                         memzero(&ret_chids[i], sizeof(EFI_GUID));
+                        continue;
+                }
+
+                get_chid(smbios_fields, chid_smbios_table[i], &ret_chids[i]);
+        }
 }