Linux Kernel up to 6.15.2 io_bitmap_exit null pointer dereference

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CTI Interest Score
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5.5$0-$5k0.92

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.15.2. This impacts the function io_bitmap_exit. The manipulation leads to null pointer dereference. This vulnerability is referenced as CVE-2025-38100. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.15.2. It has been rated as critical. This issue affects the function io_bitmap_exit. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: x86/iopl: Cure TIF_IO_BITMAP inconsistencies io_bitmap_exit() is invoked from exit_thread() when a task exists or when a fork fails. In the latter case the exit_thread() cleans up resources which were allocated during fork(). io_bitmap_exit() invokes task_update_io_bitmap(), which in turn ends up in tss_update_io_bitmap(). tss_update_io_bitmap() operates on the current task. If current has TIF_IO_BITMAP set, but no bitmap installed, tss_update_io_bitmap() crashes with a NULL pointer dereference. There are two issues, which lead to that problem: 1) io_bitmap_exit() should not invoke task_update_io_bitmap() when the task, which is cleaned up, is not the current task. That's a clear indicator for a cleanup after a failed fork(). 2) A task should not have TIF_IO_BITMAP set and neither a bitmap installed nor IOPL emulation level 3 activated. This happens when a kernel thread is created in the context of a user space thread, which has TIF_IO_BITMAP set as the thread flags are copied and the IO bitmap pointer is cleared. Other than in the failed fork() case this has no impact because kernel threads including IO workers never return to user space and therefore never invoke tss_update_io_bitmap(). Cure this by adding the missing cleanups and checks: 1) Prevent io_bitmap_exit() to invoke task_update_io_bitmap() if the to be cleaned up task is not the current task. 2) Clear TIF_IO_BITMAP in copy_thread() unconditionally. For user space forks it is set later, when the IO bitmap is inherited in io_bitmap_share(). For paranoia sake, add a warning into tss_update_io_bitmap() to catch the case, when that code is invoked with inconsistent state.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-38100 since 04/16/2025. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 243421 (Amazon Linux 2 : kernel (ALASKERNEL-5.10-2025-098)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34, 6.15.3 or 6.16-rc1 eliminates this vulnerability. Applying the patch d64b7b05a827f98d068f412969eef65489b0cf03/2dace5e016c991424a3dc6e83b1ae5dca8992d08/aa5ce1485562f20235b4c759eee5ab0c41d2c220/2cfcbe1554c119402e7382de974c26b0549899fe/b3b3b6366dc8eb5b22edba9adc4bff3cdacfd64c/73cfcc8445585b8af7e18be3c9246b851fdf336c/8b68e978718f14fdcb080c2a7791c52a0d09bc6d is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (243421) and CERT Bund (WID-SEC-2025-1452). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • Dell NetWorker
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 243421
Nessus Name: Amazon Linux 2 : kernel (ALASKERNEL-5.10-2025-098)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.239/5.15.186/6.1.142/6.6.94/6.12.34/6.15.3/6.16-rc1
Patch: d64b7b05a827f98d068f412969eef65489b0cf03/2dace5e016c991424a3dc6e83b1ae5dca8992d08/aa5ce1485562f20235b4c759eee5ab0c41d2c220/2cfcbe1554c119402e7382de974c26b0549899fe/b3b3b6366dc8eb5b22edba9adc4bff3cdacfd64c/73cfcc8445585b8af7e18be3c9246b851fdf336c/8b68e978718f14fdcb080c2a7791c52a0d09bc6d

Timelineinfo

04/16/2025 CVE reserved
07/03/2025 +78 days Advisory disclosed
07/03/2025 +0 days VulDB entry created
04/17/2026 +288 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38100 (🔒)
GCVE (CVE): GCVE-0-2025-38100
GCVE (VulDB): GCVE-100-314675
CERT Bund: WID-SEC-2025-1452 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 07/03/2025 11:36
Updated: 04/17/2026 17:47
Changes: 07/03/2025 11:36 (58), 08/05/2025 16:59 (2), 08/23/2025 14:25 (7), 09/21/2025 15:21 (1), 11/09/2025 10:21 (1), 12/06/2025 01:18 (1), 12/16/2025 18:34 (11), 04/17/2026 17:47 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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