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-rw-r--r--drivers/input/ff-core.c5
-rw-r--r--include/uapi/linux/input.h8
2 files changed, 13 insertions, 0 deletions
diff --git a/drivers/input/ff-core.c b/drivers/input/ff-core.c
index eab56c0aacd5..8f2042432c85 100644
--- a/drivers/input/ff-core.c
+++ b/drivers/input/ff-core.c
@@ -318,6 +318,11 @@ int input_ff_create(struct input_dev *dev, unsigned int max_effects)
return -EINVAL;
}
+ if (max_effects > FF_MAX_EFFECTS) {
+ dev_err(&dev->dev, "cannot allocate more than FF_MAX_EFFECTS effects\n");
+ return -EINVAL;
+ }
+
ff_dev_size = sizeof(struct ff_device) +
max_effects * sizeof(struct file *);
if (ff_dev_size < max_effects) /* overflow */
diff --git a/include/uapi/linux/input.h b/include/uapi/linux/input.h
index a8e74b45dbe2..4f9f2a0f5573 100644
--- a/include/uapi/linux/input.h
+++ b/include/uapi/linux/input.h
@@ -414,6 +414,14 @@ struct ff_effect {
#define FF_GAIN 0x60
#define FF_AUTOCENTER 0x61
+/*
+ * ff->playback(effect_id = FF_GAIN) is the first effect_id to
+ * cause a collision with another ff method, in this case ff->set_gain().
+ * Therefore the greatest safe value for effect_id is FF_GAIN - 1,
+ * and thus the total number of effects should never exceed FF_GAIN.
+ */
+#define FF_MAX_EFFECTS FF_GAIN
+
#define FF_MAX 0x7f
#define FF_CNT (FF_MAX+1)
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