CVE-2026-53385

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write<br /> <br /> A KASAN null-ptr-deref was observed in vcs_notifier():<br /> <br /> BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130<br /> Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {}<br /> <br /> The issue is a race condition in vcs_write(). When the console_lock is<br /> temporarily dropped (to copy data from userspace), the vc_data pointer<br /> obtained from vcs_vc() may become stale. After re-acquiring the lock,<br /> vcs_vc() is called again to re-validate the pointer. If the vc has been<br /> deallocated in the meantime, vcs_vc() returns NULL, and the while loop<br /> breaks (with written &gt; 0). However, after the loop, vcs_scr_updated(vc)<br /> is still called with the now-NULL vc pointer, leading to a null pointer<br /> dereference in the notifier chain (vcs_notifier dereferences param-&gt;vc).<br /> <br /> Fix this by adding a NULL check for vc before calling vcs_scr_updated().