uml: check length in exitcode_proc_write()

We don't cap the size of buffer from the user so we could write past the
end of the array here.  Only root can write to this file.

Reported-by: Nico Golde <[email protected]>
Reported-by: Fabian Yamaguchi <[email protected]>
Signed-off-by: Dan Carpenter <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
1 file changed