[Qemu-devel] [PATCH] apb: Fix out-of-bounds array write access

[Stefan Weil <sw@weilnetz.de>]

The array regs is declared with IOMMU_NREGS (3) elements and accessed
using IOMMU_CTRL (0) and IOMMU_BASE (8). In most cases, those values
are right shifted before being used as an index which results in indices
0 and 1. In one case, this right shift was missing for IOMMU_BASE which
results in an out-of-bounds write access with index 8.

The patch adds the missing shift operation also for IOMMU_CTRL where
it is needed only for cosmetic reasons.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---

Any reason why the array is declared with 3 elements when only the first 2
are used?

Regards,
Stefan

 hw/pci-host/apb.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/pci-host/apb.c b/hw/pci-host/apb.c
index 1497008..887338e 100644
--- a/hw/pci-host/apb.c
+++ b/hw/pci-host/apb.c
@@ -1,4 +1,4 @@
-/*
+re/*
  * QEMU Ultrasparc APB PCI host
  *
  * Copyright (c) 2006 Fabrice Bellard
@@ -333,7 +333,7 @@ static void iommu_config_write(void *opaque, hwaddr addr,
             is->regs[IOMMU_CTRL >> 3] &= 0xffffffffULL;
             is->regs[IOMMU_CTRL >> 3] |= val << 32;
         } else {
-            is->regs[IOMMU_CTRL] = val;
+            is->regs[IOMMU_CTRL >> 3] = val;
         }
         break;
     case IOMMU_CTRL + 0x4:
@@ -345,7 +345,7 @@ static void iommu_config_write(void *opaque, hwaddr addr,
             is->regs[IOMMU_BASE >> 3] &= 0xffffffffULL;
             is->regs[IOMMU_BASE >> 3] |= val << 32;
         } else {
-            is->regs[IOMMU_BASE] = val;
+            is->regs[IOMMU_BASE >> 3] = val;
         }
         break;
     case IOMMU_BASE + 0x4:
-- 
1.7.10.4