Linux kernel: tracing/syscalls: Use copy_from_user for the faultable syscall buffer

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

tracing/syscalls: Use copy_from_user for the faultable syscall buffer

syscall_copy_user_array() copies the buffer argument of faultable syscalls (write, pwrite64, ...) with __copy_from_user(), which skips access_ok(). Use copy_from_user() instead so a non-user address is rejected and the entry is recorded as faulted.

It could be a security concern for machines that trust perf a bit too much.