CVE-2025-40031
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: tee: fix register_shm_helper() In register_shm_helper(), fix incorrect error handling for a call to iov_iter_extract_pages(). A case is missing for when iov_iter_extract_pages() only got some pages and return a number larger than 0, but not the requested amount. This fixes a possible NULL pointer dereference following a bad input from ioctl(TEE_IOC_SHM_REGISTER) where parts of the buffer isn't mapped.
Statement
The patch fixes a NULL pointer dereference in register_shm_helper() when iov_iter_extract_pages() returns a partial success (len > 0 but fewer pages than requested). The old code didn’t handle this case, leading to a possible NULL deref upon bad userspace input via ioctl(TEE_IOC_SHM_REGISTER) (e.g., partially unmapped buffers). Impact is local kernel crash/DoS only.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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