Fix __might_sleep warning in tty/n_hdlc.c read due to copy_to_user call while current is TASK_INTERRUPTIBLE. This is a false positive since the code path does not depend on current state remaining TASK_INTERRUPTIBLE. The loop breaks out and sets TASK_RUNNING after calling copy_to_user. This patch supresses the warning by setting TASK_RUNNING before calling copy_to_user.
[1] https://syzkaller.appspot.com/bug?id=17d5de7f1fcab794cb8c40032f893f52de899324 Signed-off-by: Paul Fulghum <[email protected]> Reported-by: syzbot <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Tetsuo Handa <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Alan Cox <[email protected]> — --- a/drivers/tty/n_hdlc.c 2018-12-23 15:55:59.000000000 -0800 +++ b/drivers/tty/n_hdlc.c 2019-01-01 11:44:47.148153954 -0800 @@ -597,6 +597,7 @@ static ssize_t n_hdlc_tty_read(struct tt /* too large for caller's buffer */ ret = -EOVERFLOW; } else { + __set_current_state(TASK_RUNNING); if (copy_to_user(buf, rbuf->buf, rbuf->count)) ret = -EFAULT; else
