[PATCH v2] smbios: sanitize type from external type before checking have_fields_bitmap

[PATCH v2] smbios: sanitize type from external type before checking have_fields_bitmap

[Paolo Bonzini]

test_bit uses header->type as an offset; if the file incorrectly specifies a
type greater than 127, smbios_entry_add will read and write garbage.

To fix this, just pass the smbios data through, assuming the user knows what
to do.  Reported by Coverity as CID 1487255.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/smbios/smbios.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
index 60349ee402..4c9f664830 100644
--- a/hw/smbios/smbios.c
+++ b/hw/smbios/smbios.c
@@ -1205,13 +1205,15 @@ void smbios_entry_add(QemuOpts *opts, Error **errp)
             return;
         }
 
-        if (test_bit(header->type, have_fields_bitmap)) {
-            error_setg(errp,
-                       "can't load type %d struct, fields already specified!",
-                       header->type);
-            return;
+        if (header->type <= SMBIOS_MAX_TYPE) {
+            if (test_bit(header->type, have_fields_bitmap)) {
+                error_setg(errp,
+                           "can't load type %d struct, fields already specified!",
+                           header->type);
+                return;
+            }
+            set_bit(header->type, have_binfile_bitmap);
         }
-        set_bit(header->type, have_binfile_bitmap);
 
         if (header->type == 4) {
             smbios_type4_count++;
-- 
2.37.2

Re: [PATCH v2] smbios: sanitize type from external type before checking have_fields_bitmap

[Philippe Mathieu-Daudé via]

On Mon, Sep 5, 2022 at 10:44 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> test_bit uses header->type as an offset; if the file incorrectly specifies a
> type greater than 127, smbios_entry_add will read and write garbage.
>
> To fix this, just pass the smbios data through, assuming the user knows what
> to do.  Reported by Coverity as CID 1487255.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  hw/smbios/smbios.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>