drm/i915/guc: Annotate struct ct_incoming_msg 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 ct_incoming_msg.

Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: "Gustavo A. R. Silva" <[email protected]>
Cc: John Harrison <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: Michal Wajdeczko <[email protected]>
Cc: Matt Roper <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
Signed-off-by: Kees Cook <[email protected]>
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Reviewed-by: Andi Shyti <[email protected]>
Signed-off-by: Andi Shyti <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: kees

drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c

@@ -96,7 +96,7 @@ struct ct_request {
 struct ct_incoming_msg {
 	struct list_head link;
 	u32 size;
-	u32 msg[];
+	u32 msg[] __counted_by(size);
 };
 
 enum { CTB_SEND = 0, CTB_RECV = 1 };