Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
drm/mediatek: Fix a null pointer crash in mtk_drm_crtc_finish_page_flip
It’s possible that mtk_crtc->event is NULL in mtk_drm_crtc_finish_page_flip().
pending_needs_vblank value is set by mtk_crtc->event, but in mtk_drm_crtc_atomic_flush(), it’s is not guarded by the same lock in mtk_drm_finish_page_flip(), thus a race condition happens.
Consider the following case:
CPU1 CPU2 step 1: mtk_drm_crtc_atomic_begin() mtk_crtc->event is not null, step 1: mtk_drm_crtc_atomic_flush: mtk_drm_crtc_update_config( !!mtk_crtc->event) step 2: mtk_crtc_ddp_irq -> mtk_drm_finish_page_flip: lock mtk_crtc->event set to null, pending_needs_vblank set to false unlock pending_needs_vblank set to true,
step 2: mtk_crtc_ddp_irq -> mtk_drm_finish_page_flip called again, pending_needs_vblank is still true //null pointer
Instead of guarding the entire mtk_drm_crtc_atomic_flush(), it’s more efficient to just check if mtk_crtc->event is null before use.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Debian 10 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- linux @ 5.4.0 (+12 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 10 | Will Not Fix | — |
| Debian 10 cloud | Will Not Fix | — |
| Debian 11 | Will Not Fix |
28 kernels
|
| Debian 11 cloud | Will Not Fix |
8 kernels
|
| Proxmox VE 7 5.15 | Released |
44 kernels
|
| Ubuntu 20.04 | Planned | — |
| Ubuntu 20.04 AWS | Will Not Fix | — |
| Ubuntu 20.04 Azure | Planned | — |
| Ubuntu 20.04 GCP | Planned | — |
| Ubuntu 20.04 HWE AWS | Released |
39 kernels
|
| Ubuntu 20.04 HWE Azure | Released |
23 kernels
|
| Ubuntu 22.04 | Released |
52 kernels
|
| Ubuntu 22.04 AWS | Released |
46 kernels
|
| Ubuntu 22.04 Azure | Released |
43 kernels
|
| Ubuntu 24.04 | Released |
1 kernel
|