Re: [Qemu-devel] [PATCH v2 2/2] memory: fix possible NULL pointer dereference

[Philippe Mathieu-Daudé]

Hi Dima,

On 07/11/2018 05:34 AM, Dima Stepanov wrote:
> Gentle ping. CCing Paolo Bonzini.
> 
> Regards, Dima.
> 
> On Tue, Jun 19, 2018 at 05:12:16PM +0300, Dima Stepanov wrote:
>> Ping.
>>
>> Regards, Dima.
>>
>> On Wed, Jun 13, 2018 at 11:19:55AM +0300, Dima Stepanov wrote:
>>> In the memory_region_do_invalidate_mmio_ptr() routine the section
>>> variable is intialized by the memory_region_find() call. The section.mr
>>> field can be set to NULL.
>>>
>>> Add the check for NULL before trying to drop a section.
>>>
>>> Signed-off-by: Dima Stepanov <address@hidden>
>>> ---
>>>  memory.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/memory.c b/memory.c
>>> index 3212acc..bb45248 100644
>>> --- a/memory.c
>>> +++ b/memory.c
>>> @@ -2712,7 +2712,7 @@ static void 
>>> memory_region_do_invalidate_mmio_ptr(CPUState *cpu,
>>>      /* Reset dirty so this doesn't happen later. */
>>>      cpu_physical_memory_test_and_clear_dirty(offset, size, 1);
>>>  
>>> -    if (section.mr != mr) {
>>> +    if (section.mr && (section.mr != mr)) {

section.mr can't be NULL here.

You can give the static analyzer a hint using "assert(section.mr);"

>>>          /* memory_region_find add a ref on section.mr */
>>>          memory_region_unref(section.mr);
>>>          if (MMIO_INTERFACE(section.mr->owner)) {
>>> -- 
>>> 2.7.4
>>>

Regards,

Phil.

signature.asc
Description: OpenPGP digital signature