Commit cef98864 authored Jul 28, 2017 by Ian Abbott Committed by Greg Kroah-Hartman Jul 30, 2017

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



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>
Cc: <stable@vger.kernel.org> # 4.5+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 055655a9

drivers/staging/comedi/comedi_fops.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;