# CVE-2026-46272: coresight: tmc-etr: Fix race condition between sysfs and perf mode

> A race condition in the Linux kernel Coresight TMC ETR driver can trigger a kernel warning and potential instability when sysfs and perf modes are used simultaneously.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Jun 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-46272, DEBIAN-CVE-2026-46272, GHSA-v558-wf7v-xc9h, ROOT-OS-DEBIAN-13-CVE-2026-46272, ROOT-OS-UBUNTU-2404-CVE-2026-46272, UBUNTU-CVE-2026-46272

## What is CVE-2026-46272?

CVE-2026-46272 is a medium-severity vulnerability in Linux kernel, published on 3 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

coresight: tmc-etr: Fix race condition between sysfs and perf mode

When trying to run perf and sysfs mode simultaneously, the WARN_ON()
in tmc_etr_enable_hw() is triggered sometimes:

 WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc]
 [..snip..]
 Call trace:
  tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P)
  tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L)
  tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc]
  coresight_enable_path+0x1c8/0x218 [coresight]
  coresight_enable_sysfs+0xa4/0x228 [coresight]
  enable_source_store+0x58/0xa8 [coresight]
  dev_attr_store+0x20/0x40
  sysfs_kf_write+0x4c/0x68
  kernfs_fop_write_iter+0x120/0x1b8
  vfs_write+0x2c8/0x388
  ksys_write+0x74/0x108
  __arm64_sys_write+0x24/0x38
  el0_svc_common.constprop.0+0x64/0x148
  do_el0_svc+0x24/0x38
  el0_svc+0x3c/0x130
  el0t_64_sync_handler+0xc8/0xd0
  el0t_64_sync+0x1ac/0x1b0
 ---[ end trace 0000000000000000 ]---

Since the enablement of sysfs mode is separeted into two critical regions,
one for sysfs buffer allocation and another for hardware enablement, it's
possible to race with the perf mode. Fix this by double check whether
the perf mode's been used before enabling the hardware in sysfs mode.

 mode:
   [sysfs mode]                   [perf mode]
   tmc_etr_get_sysfs_buffer()
     spin_lock(&drvdata->spinlock)
     [sysfs buffer allocation]
     spin_unlock(&drvdata->spinlock)
                                  spin_lock(&drvdata->spinlock)
                                  tmc_etr_enable_hw()
                                    drvdata->etr_buf = etr_perf->etr_buf
                                  spin_unlock(&drvdata->spinlock)
   spin_lock(&drvdata->spinlock)
   tmc_etr_enable_hw()
     WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at
                                  the perf side
   spin_unlock(&drvdata->spinlock)

With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf.
This ensures we verify whether the perf mode's already running before we
actually allocate the buffer. Then we can save the time of
allocating/freeing the sysfs buffer if race with the perf mode.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-46272?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46272?

Apply the vendor's patch.

## Is CVE-2026-46272 being exploited?

There is no known exploitation of CVE-2026-46272 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46272 and fix it if it is affected.

What it is: CVE-2026-46272 is a medium-severity vulnerability in Linux kernel, published on 3 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46272 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46272/ (Markdown: https://insights.sbomify.com/CVE-2026-46272/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46272
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46272
- OSV: https://osv.dev/vulnerability/CVE-2026-46272

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46272/
Summaries are generated and may contain mistakes; the official description above is the record.