On Tue, May 8, 2018 at 7:16 AM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > On Wed, May 02, 2018 at 05:38:49PM -0500, Wenwen Wang wrote: >> At the end of atomisp_subdev_set_selection(), the function >> atomisp_subdev_get_rect() is invoked to get the pointer to v4l2_rect. Since >> this function may return a NULL pointer, it is firstly invoked to check >> the returned pointer. If the returned pointer is not NULL, then the >> function is invoked again to obtain the pointer and the memory content >> at the location of the returned pointer is copied to the memory location of >> r. In most cases, the pointers returned by the two invocations are same. >> However, given that the pointer returned by the function >> atomisp_subdev_get_rect() is not a constant, it is possible that the two >> invocations return two different pointers. For example, another thread may >> race to modify the related pointers during the two invocations. > > You're assuming a very serious race condition exists. > > >> In that >> case, even if the first returned pointer is not null, the second returned >> pointer might be null, which will cause issues such as null pointer >> dereference. > > And then complaining that if a really serious bug exists then this very > minor bug would exist too... If there were really a race condition like > that then we'd want to fix it instead. In other words, this is not a > real life bug fix. > > But it would be fine as a readability or static checker fix so that's > fine. Thanks for your response. From the performance perspective, this bug should also be fixed, as the second invocation is redundant if it is expected to return a same pointer as the first one. Wenwen
