CVE-2025-39807

In the Linux kernel, the following vulnerability has been resolved:

drm/mediatek: Add error handling for old state CRTC in atomic_disable

Introduce error handling to address an issue where, after a hotplug

event, the cursor continues to update. This situation can lead to a

kernel panic due to accessing the NULL `old_state->crtc`.

E,g.

Unable to handle kernel NULL pointer dereference at virtual address

Call trace:

mtk_crtc_plane_disable+0x24/0x140

mtk_plane_atomic_update+0x8c/0xa8

drm_atomic_helper_commit_planes+0x114/0x2c8

drm_atomic_helper_commit_tail_rpm+0x4c/0x158

commit_tail+0xa0/0x168

drm_atomic_helper_commit+0x110/0x120

drm_atomic_commit+0x8c/0xe0

drm_atomic_helper_update_plane+0xd4/0x128

__setplane_atomic+0xcc/0x110

drm_mode_cursor_common+0x250/0x440

drm_mode_cursor_ioctl+0x44/0x70

drm_ioctl+0x264/0x5d8

__arm64_sys_ioctl+0xd8/0x510

invoke_syscall+0x6c/0xe0

do_el0_svc+0x68/0xe8

el0_svc+0x34/0x60

el0t_64_sync_handler+0x1c/0xf8

el0t_64_sync+0x180/0x188

Adding NULL pointer checks to ensure stability by preventing operations

on an invalid CRTC state.