[ 48/74] staging: comedi: bug-fix NULL pointer dereference on failed attach

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ian Abbott <abbotti@xxxxxxxxx>

commit 3955dfa8216f712bc204a5ad2f4e51efff252fde upstream.

Commit dcd7b8bd63cb81c5b973bf86510ca3c80bbbd162 ("staging: comedi: put
module _after_ detach" by myself) reversed a couple of calls in
`comedi_device_attach()` when recovering from an error returned by the
low-level driver's 'attach' handler.  Unfortunately, that introduced a
NULL pointer dereference bug as `dev->driver` is NULL after the call to
`comedi_device_detach()`.   We still have a pointer to the low-level
comedi driver structure in the `driv` variable, so use that instead.

Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/comedi/drivers.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -464,7 +464,7 @@ int comedi_device_attach(struct comedi_d
 		ret = comedi_device_postconfig(dev);
 	if (ret < 0) {
 		comedi_device_detach(dev);
-		module_put(dev->driver->module);
+		module_put(driv->module);
 	}
 	/* On success, the driver module count has been incremented. */
 	return ret;


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/