ksmbd: Fix UAF in __close_file_table_ids

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix UAF in __close_file_table_ids A use-after-free is possible if one thread destroys the file via __ksmbd_close_fd while another thread holds a reference to it. The existing checks on fp->refcount are not sufficient to prevent this. The fix takes ft->lock around the section which removes the file from the file table. This prevents two threads acquiring the same file pointer via __close_file_table_ids, as well as the other functions which retrieve a file from the IDR and which already use this same lock.

References

• https://git.kernel.org/stable/c/fec1f9e9a650e8e7011330a085c77e7bf2a08ea9
• https://git.kernel.org/stable/c/9e9841e232b51171ddf3bc4ee517d5d28dc8cad6
• https://git.kernel.org/stable/c/16727e442568a46d9cca69fe2595896de86e120d
• https://git.kernel.org/stable/c/36991c1ccde2d5a521577c448ffe07fcccfe104d