[Qemu-devel] [PATCH] memory region: check the old.mmio.read status

[Li Qiang]

To avoid NULL-deref for the devices without read callbacks

Signed-off-by: Li Qiang <liq...@gmail.com>
---
 memory.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/memory.c b/memory.c
index 9b73892768..48d025426b 100644
--- a/memory.c
+++ b/memory.c
@@ -406,6 +406,10 @@ static MemTxResult 
memory_region_oldmmio_read_accessor(MemoryRegion *mr,
 {
     uint64_t tmp;
 
+    if (!mr->ops->old_mmio.read[ctz32(size)]) {
+        return MEMTX_DECODE_ERROR;
+    }
+
     tmp = mr->ops->old_mmio.read[ctz32(size)](mr->opaque, addr);
     if (mr->subpage) {
         trace_memory_region_subpage_read(get_cpu_index(), mr, addr, tmp, size);
-- 
2.11.0