[PATCH] dm: Annotate struct dm_stat with __counted_by

[PATCH] dm: Annotate struct dm_stat with __counted_by

[Kees Cook]

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 <agk@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: dm-devel@redhat.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 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
-- 
2.34.1

Re: [PATCH] dm: Annotate struct dm_stat with __counted_by

[Gustavo A. R. Silva]

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 <agk@redhat.com>
> Cc: Mike Snitzer <snitzer@kernel.org>
> Cc: dm-devel@redhat.com
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@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

Re: [PATCH] dm: Annotate struct dm_stat with __counted_by

[Kees Cook]

On Fri, 15 Sep 2023 13:04:01 -0700, 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.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] dm: Annotate struct dm_stat with __counted_by
      https://git.kernel.org/kees/c/e9d842d479ac

Take care,

-- 
Kees Cook