smbios: if a string value is unknown, use string number 0

The SMBIOS specification describes: "If a string field references no string,
a null (0) is placed in that string field."

Accordingly we should avoid writing a string "Unknown" to the SMBIOS table.

dmidecode displays 'Not Specified' if the string number is 0.

Commit 00a871d34e2f ("smbios: empty strings in smbios_add_string()")
correctly identified that strings may not have length 0 as two
consecutive NULs indentify the end of the string list. But the suggested
solution did not match the intent of the SMBIOS specification.

Fixes: 00a871d34e2f ("smbios: empty strings in smbios_add_string()")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

diff --git a/lib/smbios.c b/lib/smbios.c
index 0ae857855ec3b801328f2f8aa0a30e8dfbf1c63c..6190c168f26c59b8b17b408d0092a00cd4446d15 100644 (file)
--- a/lib/smbios.c
+++ b/lib/smbios.c
@@ -135,13 +135,16 @@ static const struct map_sysinfo *convert_sysinfo_to_dt(const char *node, const c
  *
  * @ctx:       SMBIOS context
  * @str:       string to add
- * Return:     string number in the string area (1 or more)
+ * Return:     string number in the string area. 0 if str is NULL.
  */
 static int smbios_add_string(struct smbios_ctx *ctx, const char *str)
 {
        int i = 1;
        char *p = ctx->eos;
 
+       if (!str)
+               return 0;
+
        for (;;) {
                if (!*p) {
                        ctx->last_str = p;
@@ -217,7 +220,7 @@ static int smbios_add_prop_si(struct smbios_ctx *ctx, const char *prop,
        int ret;
 
        if (!dval || !*dval)
-               dval = "Unknown";
+               dval = NULL;
 
        if (!prop)
                return smbios_add_string(ctx, dval);
@@ -380,19 +383,19 @@ static int smbios_write_type1(ulong *current, int handle,
        memset(t, 0, sizeof(struct smbios_type1));
        fill_smbios_header(t, SMBIOS_SYSTEM_INFORMATION, len, handle);
        smbios_set_eos(ctx, t->eos);
-       t->manufacturer = smbios_add_prop(ctx, "manufacturer", "Unknown");
-       t->product_name = smbios_add_prop(ctx, "product", "Unknown");
+       t->manufacturer = smbios_add_prop(ctx, "manufacturer", NULL);
+       t->product_name = smbios_add_prop(ctx, "product", NULL);
        t->version = smbios_add_prop_si(ctx, "version",
                                        SYSINFO_ID_SMBIOS_SYSTEM_VERSION,
-                                       "Unknown");
+                                       NULL);
        if (serial_str) {
                t->serial_number = smbios_add_prop(ctx, NULL, serial_str);
                strncpy((char *)t->uuid, serial_str, sizeof(t->uuid));
        } else {
-               t->serial_number = smbios_add_prop(ctx, "serial", "Unknown");
+               t->serial_number = smbios_add_prop(ctx, "serial", NULL);
        }
-       t->sku_number = smbios_add_prop(ctx, "sku", "Unknown");
-       t->family = smbios_add_prop(ctx, "family", "Unknown");
+       t->sku_number = smbios_add_prop(ctx, "sku", NULL);
+       t->family = smbios_add_prop(ctx, "family", NULL);
 
        len = t->length + smbios_string_table_len(ctx);
        *current += len;
@@ -411,12 +414,12 @@ static int smbios_write_type2(ulong *current, int handle,
        memset(t, 0, sizeof(struct smbios_type2));
        fill_smbios_header(t, SMBIOS_BOARD_INFORMATION, len, handle);
        smbios_set_eos(ctx, t->eos);
-       t->manufacturer = smbios_add_prop(ctx, "manufacturer", "Unknown");
-       t->product_name = smbios_add_prop(ctx, "product", "Unknown");
+       t->manufacturer = smbios_add_prop(ctx, "manufacturer", NULL);
+       t->product_name = smbios_add_prop(ctx, "product", NULL);
        t->version = smbios_add_prop_si(ctx, "version",
                                        SYSINFO_ID_SMBIOS_BASEBOARD_VERSION,
-                                       "Unknown");
-       t->asset_tag_number = smbios_add_prop(ctx, "asset-tag", "Unknown");
+                                       NULL);
+       t->asset_tag_number = smbios_add_prop(ctx, "asset-tag", NULL);
        t->feature_flags = SMBIOS_BOARD_FEATURE_HOSTING;
        t->board_type = SMBIOS_BOARD_MOTHERBOARD;
 
@@ -437,7 +440,7 @@ static int smbios_write_type3(ulong *current, int handle,
        memset(t, 0, sizeof(struct smbios_type3));
        fill_smbios_header(t, SMBIOS_SYSTEM_ENCLOSURE, len, handle);
        smbios_set_eos(ctx, t->eos);
-       t->manufacturer = smbios_add_prop(ctx, "manufacturer", "Unknown");
+       t->manufacturer = smbios_add_prop(ctx, "manufacturer", NULL);
        t->chassis_type = SMBIOS_ENCLOSURE_DESKTOP;
        t->bootup_state = SMBIOS_STATE_SAFE;
        t->power_supply_state = SMBIOS_STATE_SAFE;
@@ -455,8 +458,8 @@ static void smbios_write_type4_dm(struct smbios_type4 *t,
                                  struct smbios_ctx *ctx)
 {
        u16 processor_family = SMBIOS_PROCESSOR_FAMILY_UNKNOWN;
-       const char *vendor = "Unknown";
-       const char *name = "Unknown";
+       const char *vendor = NULL;
+       const char *name = NULL;
 
 #ifdef CONFIG_CPU
        char processor_name[49];