On 9/15/23 14:04, Kees Cook wrote:
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 dm_stat.

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

Cc: Alasdair Kergon <a...@redhat.com>
Cc: Mike Snitzer <snit...@kernel.org>
Cc: dm-devel@redhat.com
Signed-off-by: Kees Cook <keesc...@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavo...@kernel.org>

Thanks
--
Gustavo

---
  drivers/md/dm-stats.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index db2d997a6c18..bdc14ec99814 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -56,7 +56,7 @@ struct dm_stat {
        size_t percpu_alloc_size;
        size_t histogram_alloc_size;
        struct dm_stat_percpu *stat_percpu[NR_CPUS];
-       struct dm_stat_shared stat_shared[];
+       struct dm_stat_shared stat_shared[] __counted_by(n_entries);
  };
#define STAT_PRECISE_TIMESTAMPS 1

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