In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: take fl->lock when moving mmaps on interrupted invoke W

In the Linux kernel, the following vulnerability has been resolved:

misc: fastrpc: take fl->lock when moving mmaps on interrupted invoke

When an invoke is interrupted by a signal,
wait_for_completion_interruptible() returns -ERESTARTSYS and
fastrpc_internal_invoke() moves every buffer from fl->mmaps onto
cctx->invoke_interrupted_mmaps. This list_del()/list_add_tail() walk
runs without holding fl->lock, the lock that serialises fl->mmaps in
fastrpc_req_mmap() and fastrpc_req_munmap() everywhere else.

Take fl->lock around the move, matching every other fl->mmaps accessor.