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
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