dm: Annotate struct stripe_c 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 stripe_c.

[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/20230915200352.never.118-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index e2854a3cbd2826c7e8bed03f473f94ab19bf1e57..5e70f5ae394d0bd63e98ed9302946a574dac129c 100644 (file)
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -44,7 +44,7 @@ struct stripe_c {
        /* Work struct used for triggering events*/
        struct work_struct trigger_event;
 
-       struct stripe stripe[];
+       struct stripe stripe[] __counted_by(stripes);
 };
 
 /*