dm raid: Annotate struct raid_set 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 raid_set.

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

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: dm-devel@redhat.com
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230915200335.never.098-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 5f9991765f270a15da5983555251926aa45fab5c..9755788e8b785eab7a420568e9baa734e92d278f 100644 (file)
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -254,7 +254,7 @@ struct raid_set {
                int mode;
        } journal_dev;
 
-       struct raid_dev dev[];
+       struct raid_dev dev[] __counted_by(raid_disks);
 };
 
 static void rs_config_backup(struct raid_set *rs, struct rs_layout *l)