firmware: dmi_scan: Trim DMI table length before exporting it

The SMBIOS v3 entry points specify a maximum length for the DMI table,
not the exact length. Thus there may be garbage after the end-of-table
marker, which we don't want to export to user-space. Adjust dmi_len
when we find the end-of-table marker, so that only the actual table
payload is exported.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com>

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 14a8912..7fdf286 100644 (file)
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -108,6 +108,9 @@ static void dmi_decode_table(u8 *buf,
                if (data - buf < dmi_len - 1)
                        decode(dm, private_data);
 
+               data += 2;
+               i++;
+
                /*
                 * 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
@@ -118,10 +121,11 @@ static void dmi_decode_table(u8 *buf,
                 */
                if (!dmi_num && dm->type == DMI_ENTRY_END_OF_TABLE)
                        break;
-
-               data += 2;
-               i++;
        }
+
+       /* Trim DMI table length if needed */
+       if (dmi_len > data - buf)
+               dmi_len = data - buf;
 }
 
 static phys_addr_t dmi_base;
@@ -130,8 +134,9 @@ static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
                void *))
 {
        u8 *buf;
+       u32 orig_dmi_len = dmi_len;
 
-       buf = dmi_early_remap(dmi_base, dmi_len);
+       buf = dmi_early_remap(dmi_base, orig_dmi_len);
        if (buf == NULL)
                return -1;
 
@@ -139,7 +144,7 @@ static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
 
        add_device_randomness(buf, dmi_len);
 
-       dmi_early_unmap(buf, dmi_len);
+       dmi_early_unmap(buf, orig_dmi_len);
        return 0;
 }