KASAN: use-after-free Read in vkms_dumb_create

[syzbot]

Hello,

syzbot tried to test the proposed patch but build/boot failed:

failed to apply patch:
checking file drivers/gpu/drm/vkms/vkms_gem.c
patch: **** unexpected end of file in patch



Tested on:

commit:         c578ddb3 Merge tag 'linux-kselftest-5.7-rc3' of git://git...
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
dashboard link: https://syzkaller.appspot.com/bug?extid=e3372a2afe1e7ef04bc7
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=165806efe00000