On Thu, Feb 10, 2022 at 02:58:24PM +0800, Zhouyi Zhou wrote: > In function do_remove_conflicting_framebuffers, if device is NULL, there > will be null pointer reference. The patch add a check to the if expression. > > Signed-off-by: Zhouyi Zhou <zhouzhouyi@xxxxxxxxx> > --- > Dear Linux folks > > I discover this bug in the PowerPC VM provided by > Open source lab of Oregon State University: > > https://lkml.org/lkml/2022/2/8/1145 > > I found that the root cause of null device field is in offb_init_fb: > info = framebuffer_alloc(sizeof(u32) * 16, NULL); > > I have tested the patch in the PowerPC VM. Hope my patch can be correct. This looks plausible to me, but I am quite unfamiliar with this code. Thanx, Paul > Many Thanks > Zhouyi > -- > drivers/video/fbdev/core/fbmem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > index 34d6bb1bf82e..422b1fc01722 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -1579,7 +1579,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, > * If it's not a platform device, at least print a warning. A > * fix would add code to remove the device from the system. > */ > - if (dev_is_platform(device)) { > + if (device && dev_is_platform(device)) { > registered_fb[i]->forced_out = true; > platform_device_unregister(to_platform_device(device)); > } else { > -- > 2.25.1 >
