Linux Kernel CIFS Client Memory Leak Vulnerability in Domain Handling

A memory leak vulnerability has been identified in the Linux kernel's CIFS client component, specifically within the 'cifs_construct_tcon' function. This issue arises when a multiuser mount is used with a specified domain, and CIFS credentials are applied. The function 'cifs_set_cifscreds' sets the context's domain name, which is not properly freed before the function exits, leading to a memory leak. The vulnerability affects several versions of the Linux kernel.

Impact

Exploitation of this vulnerability leads to a memory leak, where allocated memory is not properly released, potentially causing increased memory usage and degradation of system performance over time.

Reproduction

To reproduce this vulnerability, mount a CIFS share with the 'domain' option specified, using a multiuser mount. After mounting the share, add CIFS credentials for the specified domain and user. Then, access a directory within the mounted share to trigger the memory leak. Finally, unmount the share and use the 'kmemleak' tool to scan for unreferenced objects, which will reveal the memory leak caused by the vulnerability.

Remediation

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