[Qemu-arm] [PATCH v1] highbank: validate register offset before access

[P J P]

From: Prasad J Pandit <address@hidden>

An 'offset' parameter sent to highbank register r/w functions
could be greater than number(NUM_REGS=0x200) of hb registers,
leading to an OOB access issue. Add check to avoid it.

Reported-by: Moguofang (Dennis mo) <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
---
 hw/arm/highbank.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

Update: log error message(via qemu_log_mask) before returning
  -> https://lists.gnu.org/archive/html/qemu-devel/2017-11/msg01914.html

diff --git a/hw/arm/highbank.c b/hw/arm/highbank.c
index 354c6b25a8..8494dc6a48 100644
--- a/hw/arm/highbank.c
+++ b/hw/arm/highbank.c
@@ -34,6 +34,7 @@
 #include "hw/ide/ahci.h"
 #include "hw/cpu/a9mpcore.h"
 #include "hw/cpu/a15mpcore.h"
+#include "qemu/log.h"
 
 #define SMP_BOOT_ADDR           0x100
 #define SMP_BOOT_REG            0x40
@@ -117,14 +118,26 @@ static void hb_regs_write(void *opaque, hwaddr offset,
         }
     }
 
+    if (offset / 4 >= NUM_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "highbank: bad write offset 0x%x\n", (uint32_t)offset);
+        return;
+    }
     regs[offset/4] = value;
 }
 
 static uint64_t hb_regs_read(void *opaque, hwaddr offset,
                              unsigned size)
 {
+    uint32_t value;
     uint32_t *regs = opaque;
-    uint32_t value = regs[offset/4];
+
+    if (offset / 4 >= NUM_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "highbank: bad read offset 0x%x\n", (uint32_t)offset);
+        return 0;
+    }
+    value = regs[offset/4];
 
     if ((offset == 0x100) || (offset == 0x108) || (offset == 0x10C)) {
         value |= 0x30000000;
-- 
2.13.6