[Qemu-devel] [PATCH 13/15] openpic: add some bounds checking for IRQ numbers

[Scott Wood]

The two checks with abort() guard against potential QEMU-internal
problems, but the EOI check stops the guest from causing updates to queue
position -1 and other havoc if it writes EOI with no interrupt in
service.

Signed-off-by: Scott Wood <address@hidden>
---
 hw/openpic.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/openpic.c b/hw/openpic.c
index 5accff5..a3fcefd 100644
--- a/hw/openpic.c
+++ b/hw/openpic.c
@@ -289,6 +289,10 @@ static void IRQ_check(OpenPICState *opp, IRQ_queue_t *q)
             irq = base + offset;
             map &= ~(1UL << offset);
 
+            if (irq >= MAX_IRQ) {
+                abort();
+            }
+
             DPRINTF("IRQ_check: irq %d set ivpr_pr=%d pr=%d\n",
                     irq, IVPR_PRIORITY(opp->src[irq].ivpr), priority);
 
@@ -428,6 +432,11 @@ static void openpic_set_irq(void *opaque, int n_IRQ, int 
level)
     OpenPICState *opp = opaque;
     IRQ_src_t *src;
 
+    if (n_IRQ >= MAX_IRQ) {
+        fprintf(stderr, "%s: IRQ %d out of range\n", __func__, n_IRQ);
+        abort();
+    }
+
     src = &opp->src[n_IRQ];
     DPRINTF("openpic: set irq %d = %d ivpr=0x%08x\n",
             n_IRQ, level, src->ivpr);
@@ -923,6 +932,12 @@ static void openpic_cpu_write_internal(void *opaque, 
hwaddr addr,
     case 0xB0: /* EOI */
         DPRINTF("EOI\n");
         s_IRQ = IRQ_get_next(opp, &dst->servicing);
+
+        if (s_IRQ < 0) {
+            DPRINTF("%s: EOI with no interrupt in service\n", __func__);
+            break;
+        }
+
         IRQ_resetbit(&dst->servicing, s_IRQ);
         /* Set up next servicing IRQ */
         s_IRQ = IRQ_get_next(opp, &dst->servicing);
-- 
1.7.9.5