firmware: dmi_scan: Only honor end-of-table for 64-bit tables

A 32-bit entry point to a DMI table says how many structures the table
contains. The SMBIOS specification explicitly says that end-of-table
markers should be ignored if they are not actually at the end of the
DMI table. So only honor the end-of-table marker for tables accessed
through 64-bit entry points, as they do not specify a structure count.

Fixes: fc43026278 ("dmi: add support for SMBIOS 3.0 64-bit entry point")
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Matt Fleming <matt.fleming@intel.com>

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 97b1616..bba843c 100644 (file)
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -89,9 +89,9 @@ static void dmi_table(u8 *buf,
 
        /*
         * Stop when we have seen all the items the table claimed to have
-        * (SMBIOS < 3.0 only) OR we reach an end-of-table marker OR we run
-        * off the end of the table (should never happen but sometimes does
-        * on bogus implementations.)
+        * (SMBIOS < 3.0 only) OR we reach an end-of-table marker (SMBIOS
+        * >= 3.0 only) OR we run off the end of the table (should never
+        * happen but sometimes does on bogus implementations.)
         */
        while ((!dmi_num || i < dmi_num) &&
               (data - buf + sizeof(struct dmi_header)) <= dmi_len) {
@@ -110,8 +110,13 @@ static void dmi_table(u8 *buf,
 
                /*
                 * 7.45 End-of-Table (Type 127) [SMBIOS reference spec v3.0.0]
+                * For tables behind a 64-bit entry point, we have no item
+                * count and no exact table length, so stop on end-of-table
+                * marker. For tables behind a 32-bit entry point, we have
+                * seen OEM structures behind the end-of-table marker on
+                * some systems, so don't trust it.
                 */
-               if (dm->type == DMI_ENTRY_END_OF_TABLE)
+               if (!dmi_num && dm->type == DMI_ENTRY_END_OF_TABLE)
                        break;
 
                data += 2;