CVE-2025-22093 in Linux
Summary
by MITRE • 04/16/2025
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: avoid NPD when ASIC does not support DMUB
ctx->dmub_srv will de NULL if the ASIC does not support DMUB, which is tested in dm_dmub_sw_init.
However, it will be dereferenced in dmub_hw_lock_mgr_cmd if should_use_dmub_lock returns true.
This has been the case since dmub support has been added for PSR1.
Fix this by checking for dmub_srv in should_use_dmub_lock.
[ 37.440832] BUG: kernel NULL pointer dereference, address: 0000000000000058
[ 37.447808] #PF: supervisor read access in kernel mode
[ 37.452959] #PF: error_code(0x0000) - not-present page
[ 37.458112] PGD 0 P4D 0
[ 37.460662] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 37.465553] CPU: 2 UID: 1000 PID: 1745 Comm: DrmThread Not tainted 6.14.0-rc1-00003-gd62e938120f0 #23 99720e1cb1e0fc4773b8513150932a07de3c6e88
[ 37.478324] Hardware name: Google Morphius/Morphius, BIOS Google_Morphius.13434.858.0 10/26/2023
[ 37.487103] RIP: 0010:dmub_hw_lock_mgr_cmd+0x77/0xb0
[ 37.492074] Code: 44 24 0e 00 00 00 00 48 c7 04 24 45 00 00 0c 40 88 74 24 0d 0f b6 02 88 44 24 0c 8b 01 89 44 24 08 85 f6 75 05 c6 44 24 0e 01 <48> 8b 7f 58 48 89 e6 ba 01 00 00 00 e8 08 3c 2a 00 65 48 8b 04 5
[ 37.510822] RSP: 0018:ffff969442853300 EFLAGS: 00010202
[ 37.516052] RAX: 0000000000000000 RBX: ffff92db03000000 RCX: ffff969442853358
[ 37.523185] RDX: ffff969442853368 RSI: 0000000000000001 RDI: 0000000000000000
[ 37.530322] RBP: 0000000000000001 R08: 00000000000004a7 R09: 00000000000004a5
[ 37.537453] R10: 0000000000000476 R11: 0000000000000062 R12: ffff92db0ade8000
[ 37.544589] R13: ffff92da01180ae0 R14: ffff92da011802a8 R15: ffff92db03000000
[ 37.551725] FS: 0000784a9cdfc6c0(0000) GS:ffff92db2af00000(0000) knlGS:0000000000000000
[ 37.559814] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 37.565562] CR2: 0000000000000058 CR3: 0000000112b1c000 CR4: 00000000003506f0
[ 37.572697] Call Trace:
[ 37.575152] <TASK>
[ 37.577258] ? __die_body+0x66/0xb0
[ 37.580756] ? page_fault_oops+0x3e7/0x4a0
[ 37.584861] ? exc_page_fault+0x3e/0xe0
[ 37.588706] ? exc_page_fault+0x5c/0xe0
[ 37.592550] ? asm_exc_page_fault+0x22/0x30
[ 37.596742] ? dmub_hw_lock_mgr_cmd+0x77/0xb0
[ 37.601107] dcn10_cursor_lock+0x1e1/0x240
[ 37.605211] program_cursor_attributes+0x81/0x190
[ 37.609923] commit_planes_for_stream+0x998/0x1ef0
[ 37.614722] update_planes_and_stream_v2+0x41e/0x5c0
[ 37.619703] dc_update_planes_and_stream+0x78/0x140
[ 37.624588] amdgpu_dm_atomic_commit_tail+0x4362/0x49f0
[ 37.629832] ? srso_return_thunk+0x5/0x5f
[ 37.633847] ? mark_held_locks+0x6d/0xd0
[ 37.637774] ? _raw_spin_unlock_irq+0x24/0x50
[ 37.642135] ? srso_return_thunk+0x5/0x5f
[ 37.646148] ? lockdep_hardirqs_on+0x95/0x150
[ 37.650510] ? srso_return_thunk+0x5/0x5f
[ 37.654522] ? _raw_spin_unlock_irq+0x2f/0x50
[ 37.658883] ? srso_return_thunk+0x5/0x5f
[ 37.662897] ? wait_for_common+0x186/0x1c0
[ 37.666998] ? srso_return_thunk+0x5/0x5f
[ 37.671009] ? drm_crtc_next_vblank_start+0xc3/0x170
[ 37.675983] commit_tail+0xf5/0x1c0
[ 37.679478] drm_atomic_helper_commit+0x2a2/0x2b0
[ 37.684186] drm_atomic_commit+0xd6/0x100
[ 37.688199] ? __cfi___drm_printfn_info+0x10/0x10
[ 37.692911] drm_atomic_helper_update_plane+0xe5/0x130
[ 37.698054] drm_mode_cursor_common+0x501/0x670
[ 37.702600] ? __cfi_drm_mode_cursor_ioctl+0x10/0x10
[ 37.707572] drm_mode_cursor_ioctl+0x48/0x70
[ 37.711851] drm_ioctl_kernel+0xf2/0x150
[ 37.715781] drm_ioctl+0x363/0x590
[ 37.719189] ? __cfi_drm_mode_cursor_ioctl+0x10/0x10
[ 37.724165] amdgpu_drm_ioctl+0x41/0x80
[ 37.728013] __se_sys_ioctl+0x7f/0xd0
[ 37.731685] do_syscall_64+0x87/0x100
[ 37.735355] ? vma_end_read+0x12/0xe0
[ 37.739024] ? srso_return_thunk+0x5/0x5f
[ 37.743041] ? find_held_lock+0x47/0xf0
[ 37.746884] ? vma_end_read+0x12/0xe0
[ 37.750552] ? srso_return_thunk+0x5/0
---truncated---
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Analysis
by VulDB Data Team • 02/15/2026
The vulnerability described in CVE-2025-22093 affects the Linux kernel's graphics subsystem, specifically within the AMD display driver component known as drm/amd/display. This issue manifests as a kernel NULL pointer dereference that can lead to system crashes or potential privilege escalation. The root cause lies in the improper handling of the dmub_srv context pointer, which is used for DMUB (Display Microcontroller Unit) support in certain ASICs. When a graphics ASIC does not support DMUB functionality, the dmub_srv pointer is correctly set to NULL during initialization through the dm_dmub_sw_init function. However, a subsequent function dmub_hw_lock_mgr_cmd fails to validate this condition before dereferencing the pointer, leading to a kernel oops and system instability.
The technical flaw occurs in the should_use_dmub_lock function which determines whether DMUB locking mechanisms should be employed. This function does not check if dmub_srv is NULL before proceeding with operations that assume its validity. The dereference happens at address 0x58, which corresponds to the offset where dmub_srv is accessed within the dmub_hw_lock_mgr_cmd function. This type of vulnerability is classified as a NULL pointer dereference under CWE-476, representing a fundamental error in pointer validation. The attack surface is primarily through graphics operations that utilize cursor updates, atomic commits, and plane management within the display subsystem, making it particularly relevant for systems running AMD graphics hardware with kernel versions affected by this issue.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable privilege escalation or denial of service conditions in environments where graphics operations are frequently performed. The call trace demonstrates how the vulnerability is triggered through normal graphics operations involving cursor management and atomic plane updates. Systems using AMD graphics hardware, particularly those with ASICs that do not support DMUB, are at risk when executing display-related operations that invoke the dmub_hw_lock_mgr_cmd function. This vulnerability directly impacts the stability and security of Linux systems running affected kernel versions, especially in server or workstation environments where continuous graphics operations are common. The exploitation pathway follows the ATT&CK framework's privilege escalation techniques, where a kernel-level NULL pointer dereference can be leveraged to gain elevated privileges or cause system instability.
The fix for CVE-2025-22093 involves implementing a proper NULL check within the should_use_dmub_lock function to ensure dmub_srv is validated before any operations that depend on its existence. This approach aligns with secure coding practices and defensive programming principles that mandate checking all pointer validity before dereferencing. The mitigation strategy requires updating to a patched kernel version that includes the fix, which specifically adds a condition to verify dmub_srv is not NULL before proceeding with DMUB operations. Organizations should prioritize this update, particularly those running AMD graphics workloads, as the vulnerability could be exploited in scenarios involving frequent cursor updates or atomic display plane operations. Additionally, system administrators should monitor for similar patterns in other kernel subsystems and ensure that all graphics-related operations properly validate context pointers to prevent analogous NULL pointer dereference conditions.