CVE-2023-53643
Description
A race condition leading to NULL pointer dereference was found in the Linux kernel NVMe-over-TCP driver's error recovery handling. A local user with privileges to execute NVMe management commands can run the 'nvme list' command while NVMe-over-TCP error recovery work is temporarily failing reconnect attempts and cycling sockets, causing the driver to call getsockname() on a released socket pointer, which results in a NULL pointer dereference and denial of service through kernel crash.
Statement
The issue arises because of insufficient synchronization between error recovery operations and socket information queries. When an NVMe-over-TCP connection experiences errors, the error recovery work releases the existing socket and creates a new one to establish a fresh connection. During this transition, there is a window where the socket pointer may be NULL or point to freed memory. If userspace executes the 'nvme list' command during this window, the kernel attempts to gather connection information by calling getsockname() on the socket. Without proper validation, this results in dereferencing a NULL or invalid pointer, causing an immediate kernel crash. The race window is narrow, requiring error recovery to be actively cycling sockets when the list command executes. While this reliably causes crashes when the race is won, NULL pointer dereferences on modern kernels with SMAP/SMEP protections cannot be exploited for code execution or information disclosure, only denial of service.
Mitigation
To mitigate this issue, prevent the nvme_tcp module from loading. See https://access.redhat.com/solutions/41278 for instructions on blacklisting kernel modules.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.7 | 5.5 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | High | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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