Currently the user can specify a non-zero value for ff_effects_max,
without setting the EV_FF bit.
Inversely,
the user can also set ff_effects_max to zero with the EV_FF bit set,
in this case the uninitialized method ff->upload can be dereferenced,
resulting in a kernel oops.
Instead of adding a check in uinput_create_device() and
omitting setup of ff-core infrastructure silently in case the check fails,
perform the check early in uinput_setup_device(),
and print a helpful message and return -EINVAL in case the check fails.
Signed-off-by: Elias Vanderstuyft <elias.vds@xxxxxxxxx>
---
drivers/input/misc/uinput.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 345df9b..3a90a16 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -393,6 +393,21 @@ static int uinput_setup_device(struct uinput_device *udev,
if (IS_ERR(user_dev))
return PTR_ERR(user_dev);
+ if (!!user_dev->ff_effects_max ^ test_bit(EV_FF, dev->evbit)) {
+ if (user_dev->ff_effects_max)
+ printk(KERN_DEBUG
+ "%s: ff_effects_max (%u) should be zero "
+ "when FF_BIT is not set\n",
+ UINPUT_NAME, user_dev->ff_effects_max);
+ else
+ printk(KERN_DEBUG
+ "%s: ff_effects_max should be non-zero "
+ "when FF_BIT is set\n",
+ UINPUT_NAME);
+ retval = -EINVAL;
+ goto exit;
+ }
+
udev->ff_effects_max = user_dev->ff_effects_max;
/* Ensure name is filled in */
--
1.9.3
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