4.20-stable review patch. If anyone has any objections, please let me know.
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From: Paul Fulghum paulkf@microgate.com
commit fc01d8c61ce02c034e67378cd3e645734bc18c8c upstream.
Fix __might_sleep warning[1] 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=17d5de7f1fcab794cb8c40032f893f52de89932...
Signed-off-by: Paul Fulghum paulkf@microgate.com Reported-by: syzbot syzbot+c244af085a0159d22879@syzkaller.appspotmail.com Cc: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Cc: Alan Cox alan@lxorguk.ukuu.org.uk Cc: stable stable@vger.kernel.org Acked-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/n_hdlc.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/tty/n_hdlc.c +++ b/drivers/tty/n_hdlc.c @@ -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