Re: [PATCH v3 05/28] block/qcow2-bitmap: Replace g_memdup() by g_memdup2()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 9/3/21 11:13 PM, Eric Blake wrote:
> On Fri, Sep 03, 2021 at 07:44:47PM +0200, Philippe Mathieu-Daudé wrote:
>> Per https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538
>>
>>   The old API took the size of the memory to duplicate as a guint,
>>   whereas most memory functions take memory sizes as a gsize. This
>>   made it easy to accidentally pass a gsize to g_memdup(). For large
>>   values, that would lead to a silent truncation of the size from 64
>>   to 32 bits, and result in a heap area being returned which is
>>   significantly smaller than what the caller expects. This can likely
>>   be exploited in various modules to cause a heap buffer overflow.
>>
>> Replace g_memdup() by the safer g_memdup2() wrapper.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>>  block/qcow2-bitmap.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
>> index 8fb47315515..218a0dc712a 100644
>> --- a/block/qcow2-bitmap.c
>> +++ b/block/qcow2-bitmap.c
>> @@ -1599,7 +1599,7 @@ bool qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
>>                             name);
>>                  goto fail;
>>              }
>> -            tb = g_memdup(&bm->table, sizeof(bm->table));
>> +            tb = g_memdup2(&bm->table, sizeof(bm->table));
> 
> Trivially safe.  It might be worth a comment in the various commit
> messages for which patches are trivially safe (because the argument
> was directly from sizeof), and which would require a larger audit of
> callers to see if we had any (unlikely) bug (such as patch 3/28).

Yes, will do.

> Reviewed-by: Eric Blake <eblake@redhat.com>

Thanks!