---
id: CVE-2026-45878
title: 'drm/amdkfd: Fix watch_id bounds checking in debug address watch v2'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  drm/amdkfd: Fix watch_id bounds checking in debug address watch v2

  The address watch clear code receives watch_id as an unsigned value
  (u32), but some helper functions…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e <
    971bf8e61e9b4abaacf9b35eaf76ec222758f9d6
  - >-
    Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e <
    a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488
  - >-
    Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e <
    2b36c0c1bcbbe15f6cfa9652084b3124c835a150
  - >-
    Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e <
    3c38a0f07aa2bfef2b219b1f045534ad93f85afd
  - >-
    Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e <
    5a19302cab5cec7ae7f1a60c619951e6c17d8742
  - Linux 6.5
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:18:15.974841Z'
published: '2026-05-27'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:20:46.204Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-45878'
references:
  - url: 'https://git.kernel.org/stable/c/971bf8e61e9b4abaacf9b35eaf76ec222758f9d6'
  - url: 'https://git.kernel.org/stable/c/a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488'
  - url: 'https://git.kernel.org/stable/c/2b36c0c1bcbbe15f6cfa9652084b3124c835a150'
  - url: 'https://git.kernel.org/stable/c/3c38a0f07aa2bfef2b219b1f045534ad93f85afd'
  - url: 'https://git.kernel.org/stable/c/5a19302cab5cec7ae7f1a60c619951e6c17d8742'
tags:
  - cve.org
epss: 0.00182
epssPercentile: 0.07282
ingestedAt: '2026-10-16T17:24:46.699Z'
---

## Overview

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

drm/amdkfd: Fix watch_id bounds checking in debug address watch v2

The address watch clear code receives watch_id as an unsigned value
(u32), but some helper functions were using a signed int and checked
bits by shifting with watch_id.

If a very large watch_id is passed from userspace, it can be converted
to a negative value.  This can cause invalid shifts and may access
memory outside the watch_points array.

drm/amdkfd: Fix watch_id bounds checking in debug address watch v2

Fix this by checking that watch_id is within MAX_WATCH_ADDRESSES before
using it.  Also use BIT(watch_id) to test and clear bits safely.

This keeps the behavior unchanged for valid watch IDs and avoids
undefined behavior for invalid ones.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_debug.c:448
kfd_dbg_trap_clear_dev_address_watch() error: buffer overflow
'pdd->watch_points' 4 <= u32max user_rl='0-3,2147483648-u32max' uncapped

drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_debug.c
    433 int kfd_dbg_trap_clear_dev_address_watch(struct kfd_process_device *pdd,
    434                                         uint32_t watch_id)
    435 {
    436         int r;
    437
    438         if (!kfd_dbg_owns_dev_watch_id(pdd, watch_id))

kfd_dbg_owns_dev_watch_id() doesn't check for negative values so if
watch_id is larger than INT_MAX it leads to a buffer overflow.
(Negative shifts are undefined).

    439                 return -EINVAL;
    440
    441         if (!pdd->dev->kfd->shared_resources.enable_mes) {
    442                 r = debug_lock_and_unmap(pdd->dev->dqm);
    443                 if (r)
    444                         return r;
    445         }
    446
    447         amdgpu_gfx_off_ctrl(pdd->dev->adev, false);
--> 448         pdd->watch_points[watch_id] = pdd->dev->kfd2kgd->clear_address_watch(
    449                                                         pdd->dev->adev,
    450                                                         watch_id);

v2: (as per, Jonathan Kim)
 - Add early watch_id >= MAX_WATCH_ADDRESSES validation in the set path to
   match the clear path.
 - Drop the redundant bounds check in kfd_dbg_owns_dev_watch_id().

## Affected

- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 971bf8e61e9b4abaacf9b35eaf76ec222758f9d6`
- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488`
- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 2b36c0c1bcbbe15f6cfa9652084b3124c835a150`
- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 3c38a0f07aa2bfef2b219b1f045534ad93f85afd`
- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 5a19302cab5cec7ae7f1a60c619951e6c17d8742`
- `Linux 6.5`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.