On Fri, Jul 28, 2017 at 04:22:31PM +0100, Ian Abbott wrote: > 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 <piotrgre...@rsyncme.org> > Signed-off-by: Ian Abbott <abbo...@mev.co.uk> > Cc: <sta...@vger.kernel.org> # 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 >
Hi Ian, I will be able to test this in a couple of days. cheers, Piotr
