[PATCH] gpiolib: sanitize flags before allocating memory in lineevent_create()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszew...@baylibre.com>

Move all the flags sanitization before any memory allocation in
lineevent_create() in order to remove a couple unneeded gotos.

Signed-off-by: Bartosz Golaszewski <bgolaszew...@baylibre.com>
---
 drivers/gpio/gpiolib.c | 42 ++++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d9074191edef..194b0bcdcfb7 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -899,6 +899,24 @@ static int lineevent_create(struct gpio_device *gdev, void 
__user *ip)
 
        if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
                return -EFAULT;
+       
+       offset = eventreq.lineoffset;
+       lflags = eventreq.handleflags;
+       eflags = eventreq.eventflags;
+
+       if (offset >= gdev->ngpio)
+               return -EINVAL;
+
+       /* Return an error if a unknown flag is set */
+       if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
+           (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
+               return -EINVAL;
+
+       /* This is just wrong: we don't look for events on output lines */
+       if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
+           (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
+           (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
+               return -EINVAL;
 
        le = kzalloc(sizeof(*le), GFP_KERNEL);
        if (!le)
@@ -917,30 +935,6 @@ static int lineevent_create(struct gpio_device *gdev, void 
__user *ip)
                }
        }
 
-       offset = eventreq.lineoffset;
-       lflags = eventreq.handleflags;
-       eflags = eventreq.eventflags;
-
-       if (offset >= gdev->ngpio) {
-               ret = -EINVAL;
-               goto out_free_label;
-       }
-
-       /* Return an error if a unknown flag is set */
-       if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
-           (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) {
-               ret = -EINVAL;
-               goto out_free_label;
-       }
-
-       /* This is just wrong: we don't look for events on output lines */
-       if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
-           (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
-           (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)) {
-               ret = -EINVAL;
-               goto out_free_label;
-       }
-
        desc = &gdev->descs[offset];
        ret = gpiod_request(desc, le->label);
        if (ret)
-- 
2.21.0