arm: check bit index before use

From: Prasad J Pandit <[email protected]>

While performing gpio write via strongarm_gpio_handler_update routine, the 'bit' index could access beyond s->handler[28] array. Add check to avoid OOB access.

---
 hw/arm/strongarm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index ec2627374d..3dda75feaf 100644
@@ -532,7 +532,9 @@ static void strongarm_gpio_handler_update(StrongARMGPIOInfo *s)
 
     for (diff = s->prev_level ^ level; diff; diff ^= 1 << bit) {
         bit = ctz32(diff);
-        qemu_set_irq(s->handler[bit], (level >> bit) & 1);
+        if (bit < sizeof(s->handler) / sizeof(s->handler[0])) {
+            qemu_set_irq(s->handler[bit], (level >> bit) & 1);
+        }
     }
 
     s->prev_level = level;

2.17.2

2018-10-22

liqsub1

发件人：P J P <[email protected]>
发送时间：2018-10-23 01:39
主题：[Qemu-devel] [PATCH 1/3] arm: check bit index before use
收件人："Qemu Developers"<[email protected]>
抄送："Peter Maydell"<[email protected]>,"Moguofang"<[email protected]>,"Prasad J Pandit"<[email protected]>

From: Prasad J Pandit <[email protected]>

While performing gpio write via strongarm_gpio_handler_update routine, the 'bit' index could access beyond s->handler[28] array. Add check to avoid OOB access.

---

 hw/arm/strongarm.c | 4 +++- 
 1 file changed, 3 insertions(+), 1 deletion(-) 

index ec2627374d..3dda75feaf 100644 
@@ -532,7 +532,9 @@ static void strongarm_gpio_handler_update(StrongARMGPIOInfo *s) 
  
     for (diff = s->prev_level ^ level; diff; diff ^= 1 << bit) { 
         bit = ctz32(diff); 
-        qemu_set_irq(s->handler[bit], (level >> bit) & 1); 
+        if (bit < sizeof(s->handler) / sizeof(s->handler[0])) { 
 

Hello Prasad,
Maybe you can use ARRAY_SIZE here.

Thanks,
Li Qiang

+ qemu_set_irq(s->handler[bit], (level >> bit) & 1);
+ }

     } 



  
     s->prev_level = level; 

2.17.2 

+-- On Mon, 22 Oct 2018, liqsub1 wrote --+
| +        if (bit < sizeof(s->handler) / sizeof(s->handler[0])) { 
| 
| Maybe you can use ARRAY_SIZE here.

Yes, sent patch v1.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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