Linux Kernel CIFS Module Stack Buffer Overflow Vulnerability During Encryption Operations

A vulnerability in the CIFS (Common Internet File System) module of the Linux kernel has been identified, which can lead to a stack buffer overflow. This issue occurs when the CIFS module processes encryption for SMB2 (Server Message Block version 2) requests. The vulnerability arises because the encryption routine attempts to write to a buffer that is allocated in the stack's vmalloc area. This mismanagement of memory access can cause the write operation to cross a page boundary, leading to a kernel oops, which is a type of error indicating that the kernel has encountered a problem it cannot handle. The issue was discovered while running xfstests against Azure on an arm64 system.

Impact

Exploitation of this vulnerability causes a kernel oops, indicating a serious error that can potentially be exploited to execute arbitrary code or cause a denial-of-service condition by crashing the system.

Reproduction

The vulnerability can be reproduced by running the CIFS module's encryption operations on SMB2 requests that involve vmalloc'd buffers. This can be done using xfstests on an arm64 system.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been patched. Instructions for upgrading can be found in the official Linux kernel documentation.