linux-cve-announce - CVE-2025-40225: drm/panthor: Fix kernel panic on partial unmap of a GPU VA region

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Message-ID: <2025120458-CVE-2025-40225-011a@gregkh>
Date: Thu,  4 Dec 2025 16:32:00 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40225: drm/panthor: Fix kernel panic on partial unmap of a GPU VA region

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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

drm/panthor: Fix kernel panic on partial unmap of a GPU VA region

This commit address a kernel panic issue that can happen if Userspace
tries to partially unmap a GPU virtual region (aka drm_gpuva).
The VM_BIND interface allows partial unmapping of a BO.

Panthor driver pre-allocates memory for the new drm_gpuva structures
that would be needed for the map/unmap operation, done using drm_gpuvm
layer. It expected that only one new drm_gpuva would be needed on umap
but a partial unmap can require 2 new drm_gpuva and that's why it
ended up doing a NULL pointer dereference causing a kernel panic.

Following dump was seen when partial unmap was exercised.
 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000078
 Mem abort info:
   ESR = 0x0000000096000046
   EC = 0x25: DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
   FSC = 0x06: level 2 translation fault
 Data abort info:
   ISV = 0, ISS = 0x00000046, ISS2 = 0x00000000
   CM = 0, WnR = 1, TnD = 0, TagAccess = 0
   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
 user pgtable: 4k pages, 48-bit VAs, pgdp=000000088a863000
 [000000000000078] pgd=080000088a842003, p4d=080000088a842003, pud=0800000884bf5003, pmd=0000000000000000
 Internal error: Oops: 0000000096000046 [#1] PREEMPT SMP
 <snip>
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : panthor_gpuva_sm_step_remap+0xe4/0x330 [panthor]
 lr : panthor_gpuva_sm_step_remap+0x6c/0x330 [panthor]
 sp : ffff800085d43970
 x29: ffff800085d43970 x28: ffff00080363e440 x27: ffff0008090c6000
 x26: 0000000000000030 x25: ffff800085d439f8 x24: ffff00080d402000
 x23: ffff800085d43b60 x22: ffff800085d439e0 x21: ffff00080abdb180
 x20: 0000000000000000 x19: 0000000000000000 x18: 0000000000000010
 x17: 6e656c202c303030 x16: 3666666666646466 x15: 393d61766f69202c
 x14: 312d3d7361203a70 x13: 303030323d6e656c x12: ffff80008324bf58
 x11: 0000000000000003 x10: 0000000000000002 x9 : ffff8000801a6a9c
 x8 : ffff00080360b300 x7 : 0000000000000000 x6 : 000000088aa35fc7
 x5 : fff1000080000000 x4 : ffff8000842ddd30 x3 : 0000000000000001
 x2 : 0000000100000000 x1 : 0000000000000001 x0 : 0000000000000078
 Call trace:
  panthor_gpuva_sm_step_remap+0xe4/0x330 [panthor]
  op_remap_cb.isra.22+0x50/0x80
  __drm_gpuvm_sm_unmap+0x10c/0x1c8
  drm_gpuvm_sm_unmap+0x40/0x60
  panthor_vm_exec_op+0xb4/0x3d0 [panthor]
  panthor_vm_bind_exec_sync_op+0x154/0x278 [panthor]
  panthor_ioctl_vm_bind+0x160/0x4a0 [panthor]
  drm_ioctl_kernel+0xbc/0x138
  drm_ioctl+0x240/0x500
  __arm64_sys_ioctl+0xb0/0xf8
  invoke_syscall+0x4c/0x110
  el0_svc_common.constprop.1+0x98/0xf8
  do_el0_svc+0x24/0x38
  el0_svc+0x40/0xf8
  el0t_64_sync_handler+0xa0/0xc8
  el0t_64_sync+0x174/0x178

The Linux kernel CVE team has assigned CVE-2025-40225 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.10 with commit 647810ec247641eb5aec8caef818919a4518a0b1 and fixed in 6.12.56 with commit efe6dced3512066ebee2cf7c4c38d1c99625814e
	Issue introduced in 6.10 with commit 647810ec247641eb5aec8caef818919a4518a0b1 and fixed in 6.17.6 with commit e9c19d19dd7e08db89cead5b0337c18590dc6645
	Issue introduced in 6.10 with commit 647810ec247641eb5aec8caef818919a4518a0b1 and fixed in 6.18 with commit 4eabd0d8791eaf9a7b114ccbf56eb488aefe7b1f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-40225
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/gpu/drm/panthor/panthor_mmu.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/efe6dced3512066ebee2cf7c4c38d1c99625814e
	https://git.kernel.org/stable/c/e9c19d19dd7e08db89cead5b0337c18590dc6645
	https://git.kernel.org/stable/c/4eabd0d8791eaf9a7b114ccbf56eb488aefe7b1f