There is an issue when using memory_region_dispatch_read() or
memory_region_dispatch_write() on RAM memory regions.
RAM memory regions are initialized as:
memory_region_init_ram()
-> memory_region_init_ram_nomigrate()
-> memory_region_init_ram_shared_nomigrate()
-> memory_region_init()
-> object_initialize(TYPE_MEMORY_REGION)
-> memory_region_initfn()
-> mr->ops = &unassigned_mem_ops;
Later when accessing the alias, the memory_region_dispatch_read()
flow is:
memory_region_dispatch_read()
-> memory_region_dispatch_read1()
-> if (mr->ops->read) { ... }
^^^^^^
NULL deref as unassigned_mem_ops.read is NULL.
memory_region_dispatch_write()
-> if (mr->ops->write) { ... }
^^^^^^^
NULL deref as unassigned_mem_ops.read is NULL.
Fix by initializing the MemoryRegionOps to ram_device_mem_ops,
this way the memory accesses are properly dispatched using
memory_region_ram_device_read() / memory_region_ram_device_write().
Fixes: 4a2e242bbb ("memory: Don't use memcpy for ram_device regions")
Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org>
---
softmmu/memory.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/softmmu/memory.c b/softmmu/memory.c
index af25987518..2fce3fef2d 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -1509,6 +1509,8 @@ void memory_region_init_ram_shared_nomigrate(MemoryRegion
*mr,
Error *err = NULL;
memory_region_init(mr, owner, name, size);
mr->ram = true;
+ mr->ops = &ram_device_mem_ops;
+ mr->opaque = mr;
mr->terminates = true;
mr->destructor = memory_region_destructor_ram;
mr->ram_block = qemu_ram_alloc(size, share, mr, &err);
@@ -1533,6 +1535,8 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr,
Error *err = NULL;
memory_region_init(mr, owner, name, size);
mr->ram = true;
+ mr->ops = &ram_device_mem_ops;
+ mr->opaque = mr;
mr->terminates = true;
mr->destructor = memory_region_destructor_ram;
mr->ram_block = qemu_ram_alloc_resizeable(size, max_size, resized,
@@ -1558,6 +1562,8 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
Error *err = NULL;
memory_region_init(mr, owner, name, size);
mr->ram = true;
+ mr->ops = &ram_device_mem_ops;
+ mr->opaque = mr;
mr->terminates = true;
mr->destructor = memory_region_destructor_ram;
mr->align = align;
@@ -1581,6 +1587,8 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr,
Error *err = NULL;
memory_region_init(mr, owner, name, size);
mr->ram = true;
+ mr->ops = &ram_device_mem_ops;
+ mr->opaque = mr;
mr->terminates = true;
mr->destructor = memory_region_destructor_ram;
mr->ram_block = qemu_ram_alloc_from_fd(size, mr,
@@ -1603,6 +1611,8 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
{
memory_region_init(mr, owner, name, size);
mr->ram = true;
+ mr->ops = &ram_device_mem_ops;
+ mr->opaque = mr;
mr->terminates = true;
mr->destructor = memory_region_destructor_ram;
mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
--
2.21.3
