CVE-2026-43236

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

drm/atmel-hlcdc: fix use-after-free of drm_crtc_commit after release

The atmel_hlcdc_plane_atomic_duplicate_state() callback was copying the atmel_hlcdc_plane state structure without properly duplicating the drm_plane_state. In particular, state->commit remained set to the old state commit, which can lead to a use-after-free in the next drm_atomic_commit() call.

Fix this by calling __drm_atomic_helper_duplicate_plane_state(), which correctly clones the base drm_plane_state (including the ->commit pointer).

It has been seen when closing and re-opening the device node while another DRM client (e.g. fbdev) is still attached:

============================================================================= BUG kmalloc-64 (Not tainted): Poison overwritten

0xc611b344-0xc611b344 @offset=836. First byte 0x6a instead of 0x6b FIX kmalloc-64: Restoring Poison 0xc611b344-0xc611b344=0x6b Allocated in drm_atomic_helper_setup_commit+0x1e8/0x7bc age=178 cpu=0 pid=29 drm_atomic_helper_setup_commit+0x1e8/0x7bc drm_atomic_helper_commit+0x3c/0x15c drm_atomic_commit+0xc0/0xf4 drm_framebuffer_remove+0x4cc/0x5a8 drm_mode_rmfb_work_fn+0x6c/0x80 process_one_work+0x12c/0x2cc worker_thread+0x2a8/0x400 kthread+0xc0/0xdc ret_from_fork+0x14/0x28 Freed in drm_atomic_helper_commit_hw_done+0x100/0x150 age=8 cpu=0 pid=169 drm_atomic_helper_commit_hw_done+0x100/0x150 drm_atomic_helper_commit_tail+0x64/0x8c commit_tail+0x168/0x18c drm_atomic_helper_commit+0x138/0x15c drm_atomic_commit+0xc0/0xf4 drm_atomic_helper_set_config+0x84/0xb8 drm_mode_setcrtc+0x32c/0x810 drm_ioctl+0x20c/0x488 sys_ioctl+0x14c/0xc20 ret_fast_syscall+0x0/0x54 Slab 0xef8bc360 objects=21 used=16 fp=0xc611b7c0 flags=0x200(workingset|zone=0) Object 0xc611b340 @offset=832 fp=0xc611b7c0

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/549c6db503dbb85dbff4840830971853feac6625
• https://git.kernel.org/stable/c/6404898af86d986db1dbbe06177c143e40652e49
• https://git.kernel.org/stable/c/796e77c14c4c1e2cd36473760fb6cc66c695eb47
• https://git.kernel.org/stable/c/7b4d0fab3ff2c00c6d34e1952c9df5129a826aee
• https://git.kernel.org/stable/c/a205740a7231e967ac77cb731171642901c327af
• https://git.kernel.org/stable/c/ac2d898da5095d46bd1ff8585fdd753d58ad91e7
• https://git.kernel.org/stable/c/bc847787233277a337788568e90a6ee1557595eb
• https://git.kernel.org/stable/c/fd4a4d0711f48a99b25bcd45e00eef8339eff82d