Smatch complains about max_effects because it's an int and we cap the
maximum size, but we don't check for negative. A negative value here
could make "ff" smaller than sizeof(struct ff_device) and lead to
memory corruption.
I think max_effects can come from ->ff_effects_max in
uinput_setup_device() and that comes from the user so potentially
it could be negative. The call path is that uinput_setup_device()
sets the value in the ->private_data struct. From there it is:
-> uinput_ioctl_handler()
-> uinput_create_device()
-> input_ff_create(dev, udev->ff_effects_max);
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
diff --git a/drivers/input/ff-core.c b/drivers/input/ff-core.c
index 3367f76..12422ed 100644
--- a/drivers/input/ff-core.c
+++ b/drivers/input/ff-core.c
@@ -319,6 +319,12 @@ int input_ff_create(struct input_dev *dev, int max_effects)
return -EINVAL;
}
+ if (max_effects < 0)
+ return -EINVAL;
+ if (sizeof(struct ff_device) + max_effects * sizeof(struct file *) <
+ max_effects)
+ return -EINVAL;
+
ff = kzalloc(sizeof(struct ff_device) +
max_effects * sizeof(struct file *), GFP_KERNEL);
if (!ff)
--
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