CVE-2024-43895 in Linux
Summary
by MITRE • 08/26/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Skip Recompute DSC Params if no Stream on Link
[why]
Encounter NULL pointer dereference uner mst + dsc setup.
BUG: kernel NULL pointer dereference, address: 0000000000000008 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 4 PID: 917 Comm: sway Not tainted 6.3.9-arch1-1 #1 124dc55df4f5272ccb409f39ef4872fc2b3376a2 Hardware name: LENOVO 20NKS01Y00/20NKS01Y00, BIOS R12ET61W(1.31 ) 07/28/2022 RIP: 0010:drm_dp_atomic_find_time_slots+0x5e/0x260 [drm_display_helper]
Code: 01 00 00 48 8b 85 60 05 00 00 48 63 80 88 00 00 00 3b 43 28 0f 8d 2e 01 00 00 48 8b 53 30 48 8d 04 80 48 8d 04 c2 48 8b 40 18 8> RSP: 0018:ffff960cc2df77d8 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff8afb87e81280 RCX: 0000000000000224 RDX: ffff8afb9ee37c00 RSI: ffff8afb8da1a578 RDI: ffff8afb87e81280 RBP: ffff8afb83d67000 R08: 0000000000000001 R09: ffff8afb9652f850 R10: ffff960cc2df7908 R11: 0000000000000002 R12: 0000000000000000 R13: ffff8afb8d7688a0 R14: ffff8afb8da1a578 R15: 0000000000000224 FS: 00007f4dac35ce00(0000) GS:ffff8afe30b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 000000010ddc6000 CR4: 00000000003506e0 Call Trace:
? __die+0x23/0x70 ? page_fault_oops+0x171/0x4e0 ? plist_add+0xbe/0x100 ? exc_page_fault+0x7c/0x180 ? asm_exc_page_fault+0x26/0x30 ? drm_dp_atomic_find_time_slots+0x5e/0x260 [drm_display_helper 0e67723696438d8e02b741593dd50d80b44c2026]
? drm_dp_atomic_find_time_slots+0x28/0x260 [drm_display_helper 0e67723696438d8e02b741593dd50d80b44c2026]
compute_mst_dsc_configs_for_link+0x2ff/0xa40 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
? fill_plane_buffer_attributes+0x419/0x510 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
compute_mst_dsc_configs_for_state+0x1e1/0x250 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
amdgpu_dm_atomic_check+0xecd/0x1190 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
drm_atomic_check_only+0x5c5/0xa40 drm_mode_atomic_ioctl+0x76e/0xbc0
[how]
dsc recompute should be skipped if no mode change detected on the new request. If detected, keep checking whether the stream is already on current state or not.
(cherry picked from commit 8151a6c13111b465dbabe07c19f572f7cbd16fef)
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Analysis
by VulDB Data Team • 12/29/2025
The vulnerability resides within the linux kernel's display subsystem, specifically in the drm/amd/display driver component where a null pointer dereference occurs during mst (multi-stream transport) and dsc (display stream compression) configurations. This flaw manifests when the system attempts to recompute dsc parameters without first verifying whether any streams exist on the link, leading to a kernel panic due to accessing invalid memory addresses. The error trace shows execution flow through drm_dp_atomic_find_time_slots function where the null pointer dereference occurs at address 0x0000000000000008, indicating that a pointer expected to contain valid stream information is instead pointing to null.
The technical root cause involves improper state validation within the display stream compression reconfiguration logic. When processing atomic display state updates, the kernel fails to check if streams are present on the link before attempting to compute dsc parameters for those streams. This violates standard defensive programming practices and can be classified under CWE-476 as null pointer dereference. The issue specifically impacts systems using AMD graphics hardware with mst and dsc capabilities where multiple display streams are managed through a single connection, commonly found in high-resolution multi-monitor setups or docking station configurations.
The operational impact of this vulnerability extends beyond simple system crashes to potentially destabilize entire desktop environments, particularly affecting window managers like sway that rely heavily on atomic display state updates. When triggered, the kernel panic results in immediate system termination requiring manual reboot, creating denial of service conditions for users engaged in productivity tasks or multimedia applications. This vulnerability affects systems running kernel versions where the fix has not been applied, making it a critical concern for enterprise environments using AMD graphics solutions with mst/dsc configurations.
Mitigation strategies should focus on implementing proper null pointer validation before stream parameter recomputation and ensuring that dsc recompute operations are only executed when actual mode changes are detected. The fix involves adding checks to determine if streams exist on the link before proceeding with dsc configuration calculations, effectively preventing the null pointer dereference condition. Organizations should prioritize kernel updates to include the patched commit 8151a6c13111b465dbabe07c19f572f7cbd16fef, which implements this defensive programming approach. System administrators should also monitor for similar patterns in other display subsystem components and consider implementing automated patch management processes to maintain system security posture against such kernel-level vulnerabilities that could enable privilege escalation or persistent denial of service attacks.