Linux Kernel NFS Reference Leak Vulnerability in NFSD

A reference leak vulnerability has been identified in the Linux kernel's NFS server component (NFSD). The issue arises in the function 'nfsd4_add_rdaccess_to_wrdeleg()', which improperly manages file references. When a client has a read share access open from a previous operation, the function overwrites the existing reference with a new one without releasing the old reference, leading to an orphaned pointer. This mismanagement can cause open conflicts on the file. Additionally, during server shutdown, the leaked references create a situation where the file cache cannot be purged properly, causing a bug in the memory cache destruction process. This vulnerability affects the Linux kernel stable tree.

Impact

The vulnerability can lead to a reference count leak, causing conflicts on file access and preventing proper cleanup of file references during server shutdown, which triggers a bug in the memory management system.

Remediation

Users can upgrade to the latest version of the Linux kernel stable tree to address this vulnerability.