copy_process(): don't use ksys_close() on cleanups

copy_process(): don't use ksys_close() on cleanups

anon_inode_getfd() should be used *ONLY* in situations when we are
guaranteed to be past the last failure point (including copying the
descriptor number to userland, at that).  And ksys_close() should
not be used for cleanups at all.

anon_inode_getfile() is there for all nontrivial cases like that.
Just use that...

Fixes: b3e583825266 ("clone: add CLONE_PIDFD")
Signed-off-by: Al Viro <[email protected]>
Reviewed-by: Jann Horn <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>