Linux Kernel NFS Subsystem Proc Net Initialization Error Handling Vulnerability

A vulnerability exists in the Linux kernel's NFS subsystem related to improper error handling during the initialization of network file system procedures. When the function nfs_fs_proc_net_init() fails, it does not clean up the corresponding entry in /proc/net/rpc/nfs. This oversight leads to a warning when the rpc_proc_exit() function attempts to remove the /proc/net/rpc directory, as it is not empty. The issue can be reproduced by forcing a failure in the nfs_fs_proc_net_init() function, which is part of the NFS client implementation.

Impact

The vulnerability can cause a warning to be logged about leaking directory entries, which may indicate a larger issue with resource management in the kernel.

Reproduction

The vulnerability can be reproduced by injecting a fault that forces the nfs_fs_proc_net_init() function to fail. This can be done using a kernel feature that allows for fault injection, which simulates errors during the execution of the function. Once the fault is injected, the nfs_fs_proc_net_init() function will fail to remove the corresponding /proc/net/rpc/nfs entry, leading to a warning when the rpc_proc_exit() function tries to clean up the directory.