[Qemu-devel] [RFC v2 5/5] hpet: fix buffer overrun on invalid state load

["Michael S. Tsirkin" <mst@redhat.com>]

CVE-2013-4527 hw/timer/hpet.c buffer overrun

hpet is a VARRAY with a uint8 size but static array of 32

To fix, make sure num_timers is valid using VMSTATE_TEST hook.

Reported-by: Anthony Liguori <anthony@codemonkey.ws>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/timer/hpet.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
index 1ee0640..67671bc 100644
--- a/hw/timer/hpet.c
+++ b/hw/timer/hpet.c
@@ -248,6 +248,22 @@ static int hpet_pre_load(void *opaque)
     return 0;
 }
 
+bool hpet_validate_num_timers(void *opaque, int version_id)
+{
+    HPETState *s = opaque;
+
+    if (s->num_timers < HPET_MIN_TIMERS) {
+        return false;
+    } else if (s->num_timers > HPET_MAX_TIMERS) {
+        return false;
+    }
+    return true;
+}
+
+static bool hpet_fix_num_timers(HPETState *s)
+{
+}
+
 static int hpet_post_load(void *opaque, int version_id)
 {
     HPETState *s = opaque;
@@ -318,6 +334,7 @@ static const VMStateDescription vmstate_hpet = {
         VMSTATE_UINT64(isr, HPETState),
         VMSTATE_UINT64(hpet_counter, HPETState),
         VMSTATE_UINT8_V(num_timers, HPETState, 2),
+        VMSTATE_TEST("num_timers in range", hpet_validate_num_timers);
         VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0,
                                     vmstate_hpet_timer, HPETTimer),
         VMSTATE_END_OF_LIST()
-- 
MST