[PATCH] dm: Annotate struct dm_bio_prison with __counted_by

[PATCH] dm: Annotate struct dm_bio_prison 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_bio_prison.

[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-bio-prison-v1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-bio-prison-v1.c b/drivers/md/dm-bio-prison-v1.c
index 92afdca760ae..9ab32abe5ed4 100644
--- a/drivers/md/dm-bio-prison-v1.c
+++ b/drivers/md/dm-bio-prison-v1.c
@@ -26,7 +26,7 @@ struct prison_region {
 struct dm_bio_prison {
 	mempool_t cell_pool;
 	unsigned int num_locks;
-	struct prison_region regions[];
+	struct prison_region regions[] __counted_by(num_locks);
 };
 
 static struct kmem_cache *_cell_cache;
-- 
2.34.1

Re: [PATCH] dm: Annotate struct dm_bio_prison 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_bio_prison.
> 
> [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-bio-prison-v1.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/dm-bio-prison-v1.c b/drivers/md/dm-bio-prison-v1.c
> index 92afdca760ae..9ab32abe5ed4 100644
> --- a/drivers/md/dm-bio-prison-v1.c
> +++ b/drivers/md/dm-bio-prison-v1.c
> @@ -26,7 +26,7 @@ struct prison_region {
>   struct dm_bio_prison {
>   	mempool_t cell_pool;
>   	unsigned int num_locks;
> -	struct prison_region regions[];
> +	struct prison_region regions[] __counted_by(num_locks);
>   };
>   
>   static struct kmem_cache *_cell_cache;

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

[Kees Cook]

On Fri, 15 Sep 2023 13:04:08 -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_bio_prison.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] dm: Annotate struct dm_bio_prison with __counted_by
      https://git.kernel.org/kees/c/1eb1f6b6c911

Take care,

-- 
Kees Cook