Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752409AbdG1PXB (ORCPT ); Fri, 28 Jul 2017 11:23:01 -0400 Received: from smtp73.iad3a.emailsrvr.com ([173.203.187.73]:45256 "EHLO smtp73.iad3a.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752145AbdG1PXA (ORCPT ); Fri, 28 Jul 2017 11:23:00 -0400 X-Auth-ID: abbotti@mev.co.uk X-Sender-Id: abbotti@mev.co.uk From: Ian Abbott To: devel@driverdev.osuosl.org Cc: Greg Kroah-Hartman , Ian Abbott , H Hartley Sweeten , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] staging: comedi: comedi_fops: do not call blocking ops when !TASK_RUNNING Date: Fri, 28 Jul 2017 16:22:31 +0100 Message-Id: <20170728152231.4521-1-abbotti@mev.co.uk> X-Mailer: git-send-email 2.13.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1507 Lines: 41 Comedi's read and write file operation handlers (`comedi_read()` and `comedi_write()`) currently call `copy_to_user()` or `copy_from_user()` whilst in the `TASK_INTERRUPTIBLE` state, which falls foul of the `might_fault()` checks when enabled. Fix it by setting the current task state back to `TASK_RUNNING` a bit earlier before calling these functions. Reported-by: Piotr Gregor Signed-off-by: Ian Abbott Cc: # 4.5+ --- Note: stable kernel versions 4.4 and earlier will need a slightly more extensive change in `comedi_write()` than provided by this patch due to a call to `mutex_lock()` whilst in the `TASK_INTERRUPTIBLE` state. --- drivers/staging/comedi/comedi_fops.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index ca11be21f64b..34ca7823255d 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2396,6 +2396,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, continue; } + set_current_state(TASK_RUNNING); wp = async->buf_write_ptr; n1 = min(n, async->prealloc_bufsz - wp); n2 = n - n1; @@ -2528,6 +2529,8 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, } continue; } + + set_current_state(TASK_RUNNING); rp = async->buf_read_ptr; n1 = min(n, async->prealloc_bufsz - rp); n2 = n - n1; -- 2.13.2