[dmidecode] [PATCH] dmidecode: Fix up invalid DMI type 34 structure length

[Jean Delvare]

Several boards have a bug where some type 34 structures have their
length incorrectly set to 0x10 instead of 0x0B. This causes the first
5 characters of the device name to be trimmed. It's easy to check and
fix, so do it, but warn.
---
 dmidecode.c |   27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

--- dmidecode.orig/dmidecode.c  2015-05-13 09:17:46.388019635 +0200
+++ dmidecode/dmidecode.c       2015-05-13 10:25:35.620144793 +0200
@@ -2928,6 +2928,29 @@ static void dmi_64bit_memory_error_addre
  * 7.35 Management Device (Type 34)
  */
 
+/*
+ * Several boards have a bug where some type 34 structures have their
+ * length incorrectly set to 0x10 instead of 0x0B. This causes the
+ * first 5 characters of the device name to be trimmed. It's easy to
+ * check and fix, so do it, but warn.
+ */
+static void dmi_fixup_type_34(struct dmi_header *h)
+{
+       u8 *p = h->data;
+       int i;
+
+       if (h->length != 0x10)
+               return;
+
+       /* Make sure the hidden data is ASCII only */
+       for (i = 0x0B; i < 0x10; i++)
+               if (p[i] < 32 || p[i] >= 127)
+                       return;
+
+       printf("Invalid entry length (%u). Fixed up to %u.\n", 0x10, 0x0B);
+       h->length = 0x0B;
+}
+
 static const char *dmi_management_device_type(u8 code)
 {
        /* 7.35.1 */
@@ -4410,6 +4433,10 @@ static void dmi_table_decode(u8 *buf, u3
                if (h.type == 1 && h.length >= 5)
                        dmi_set_vendor(dmi_string(&h, data[0x04]));
 
+               /* Fixup a common mistake */
+               if (h.type == 34)
+                       dmi_fixup_type_34(&h);
+
                /* look for the next handle */
                next = data + h.length;
                while ((unsigned long)(next - buf + 1) < len

-- 
Jean Delvare
SUSE L3 Support