[Xen-devel] [PATCH] x86/cpuidle: prevent out of bounds array access

["Jan Beulich" <JBeulich@xxxxxxxx>]

... resulting from fbeef5570c ("x86/cpuidle: get accurate C0 value with
xenpm tool").

Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -279,7 +279,7 @@ static void print_acpi_power(
     uint64_t usage[ACPI_PROCESSOR_MAX_POWER] = { 0 };
     uint64_t res_tick[ACPI_PROCESSOR_MAX_POWER] = { 0 };
     unsigned int i;
-    u8 last_state_idx;
+    signed int last_state_idx;
 
     printk("==cpu%d==\n", cpu);
     last_state_idx = power->last_state ? power->last_state->idx : -1;
@@ -298,8 +298,12 @@ static void print_acpi_power(
     last_state_update_tick = power->last_state_update_tick;
     spin_unlock_irq(&power->stat_lock);
 
-    res_tick[last_state_idx] += ticks_elapsed(last_state_update_tick, 
current_tick);
-    usage[last_state_idx]++;
+    if ( last_state_idx >= 0 )
+    {
+        res_tick[last_state_idx] += ticks_elapsed(last_state_update_tick,
+                                                  current_tick);
+        usage[last_state_idx]++;
+    }
 
     for ( i = 1; i < power->count; i++ )
     {




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel