[PATCH v2] hw/smbios: fix field corruption in type 4 table

[Julia Suvorova]

Since table type 4 of SMBIOS version 2.6 is shorter than 3.0, the
strings which follow immediately after the struct fields have been
overwritten by unconditional filling of later fields such as core_count2.
Make these fields dependent on the SMBIOS version.

Fixes: 05e27d74c7 ("hw/smbios: add core_count2 to smbios table type 4")
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2169904

Signed-off-by: Julia Suvorova <jusual@redhat.com>
---
v2:
    * add fixes tag
    * check tbl_len instead of ep_type

 hw/smbios/smbios.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
index 4869566cf5..d2007e70fb 100644
--- a/hw/smbios/smbios.c
+++ b/hw/smbios/smbios.c
@@ -750,14 +750,16 @@ static void smbios_build_type_4_table(MachineState *ms, 
unsigned instance)
     t->core_count = (ms->smp.cores > 255) ? 0xFF : ms->smp.cores;
     t->core_enabled = t->core_count;
 
-    t->core_count2 = t->core_enabled2 = cpu_to_le16(ms->smp.cores);
-
     t->thread_count = (ms->smp.threads > 255) ? 0xFF : ms->smp.threads;
-    t->thread_count2 = cpu_to_le16(ms->smp.threads);
 
     t->processor_characteristics = cpu_to_le16(0x02); /* Unknown */
     t->processor_family2 = cpu_to_le16(0x01); /* Other */
 
+    if (tbl_len == SMBIOS_TYPE_4_LEN_V30) {
+        t->core_count2 = t->core_enabled2 = cpu_to_le16(ms->smp.cores);
+        t->thread_count2 = cpu_to_le16(ms->smp.threads);
+    }
+
     SMBIOS_BUILD_TABLE_POST;
     smbios_type4_count++;
 }
-- 
2.38.1