Input: Annotate struct ff_device with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct ff_device.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20231006201739.work.350-kees@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/include/linux/input.h b/include/linux/input.h
index 49790c1bd2c43e21615fda95cbf3febb22ba6da0..de6503c0edb8efcf86e0565a52b81e7a4e378014 100644 (file)
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -562,7 +562,7 @@ struct ff_device {
 
        int max_effects;
        struct ff_effect *effects;
-       struct file *effect_owners[];
+       struct file *effect_owners[] __counted_by(max_effects);
 };
 
 int input_ff_create(struct input_dev *dev, unsigned int max_effects);