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@xxxxxxxxxxx> Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 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