Input: evdev - annotate struct evdev_client 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 checking 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 evdev_client.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922175027.work.563-kees@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 95f90699d2b17b4e42e067bf44b6deac611fdb8b..51e0c4954600196081cfbc774c5a790c21be6e48 100644 (file)
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -50,7 +50,7 @@ struct evdev_client {
        bool revoked;
        unsigned long *evmasks[EV_CNT];
        unsigned int bufsize;
-       struct input_event buffer[];
+       struct input_event buffer[] __counted_by(bufsize);
 };
 
 static size_t evdev_get_mask_cnt(unsigned int type)