CVE-2026-53385 vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write

In the Linux kernel, the following vulnerability has been resolved: vcscreen: fix null-ptr-deref in vcsnotifier during concurrent vcswrite A KASAN null-ptr-deref was observed in vcsnotifier: BUG: KASAN: null-ptr-deref in vcsnotifier+0x98/0x130 Read of size 2 at addr qmpcmdname: qmpcapabilities,...