ocfs2: annotate struct ocfs2_replay_map 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 ocfs2_replay_map.

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

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Tom Rix <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: kees

fs/ocfs2/journal.c

@@ -90,7 +90,7 @@ enum ocfs2_replay_state {
 struct ocfs2_replay_map {
 	unsigned int rm_slots;
 	enum ocfs2_replay_state rm_state;
-	unsigned char rm_replay_slots[];
+	unsigned char rm_replay_slots[] __counted_by(rm_slots);
 };
 
 static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state)