Patch "staging: comedi: comedi_fops: do not call blocking ops when !TASK_RUNNING" has been added to the 4.9-stable tree

Patch "staging: comedi: comedi_fops: do not call blocking ops when !TASK_RUNNING" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: comedi: comedi_fops: do not call blocking ops when !TASK_RUNNING

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-comedi-comedi_fops-do-not-call-blocking-ops-when-task_running.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From cef988642cdac44e910a27cb6e8166c96f86a0df Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@mev.co.uk>
Date: Fri, 28 Jul 2017 16:22:31 +0100
Subject: staging: comedi: comedi_fops: do not call blocking ops when !TASK_RUNNING

From: Ian Abbott <abbotti@mev.co.uk>

commit cef988642cdac44e910a27cb6e8166c96f86a0df upstream.

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 <piotrgregor@rsyncme.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/comedi/comedi_fops.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2385,6 +2385,7 @@ static ssize_t comedi_write(struct file
 			continue;
 		}
 
+		set_current_state(TASK_RUNNING);
 		wp = async->buf_write_ptr;
 		n1 = min(n, async->prealloc_bufsz - wp);
 		n2 = n - n1;
@@ -2517,6 +2518,8 @@ static ssize_t comedi_read(struct file *
 			}
 			continue;
 		}
+
+		set_current_state(TASK_RUNNING);
 		rp = async->buf_read_ptr;
 		n1 = min(n, async->prealloc_bufsz - rp);
 		n2 = n - n1;


Patches currently in stable-queue which might be from abbotti@mev.co.uk are

queue-4.9/staging-comedi-comedi_fops-do-not-call-blocking-ops-when-task_running.patch