On 9/22/23 10:52, 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 nd_region.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1]
> https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Dan Williams <dan.j.willi...@intel.com>
> Cc: Vishal Verma <vishal.l.ve...@intel.com>
> Cc: Dave Jiang <dave.ji...@intel.com>
> Cc: Ira Weiny <ira.we...@intel.com>
> Cc: nvd...@lists.linux.dev
> Signed-off-by: Kees Cook <keesc...@chromium.org>
Reviewed-by: Dave Jiang <dave.ji...@intel.com>
> ---
> drivers/nvdimm/nd.h | 2 +-
> drivers/nvdimm/region_devs.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index e8b9d27dbb3c..ae2078eb6a62 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -422,7 +422,7 @@ struct nd_region {
> struct nd_interleave_set *nd_set;
> struct nd_percpu_lane __percpu *lane;
> int (*flush)(struct nd_region *nd_region, struct bio *bio);
> - struct nd_mapping mapping[];
> + struct nd_mapping mapping[] __counted_by(ndr_mappings);
> };
>
> static inline bool nsl_validate_nlabel(struct nd_region *nd_region,
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index 0a81f87f6f6c..5be65fce85cf 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1028,6 +1028,7 @@ static struct nd_region *nd_region_create(struct
> nvdimm_bus *nvdimm_bus,
>
> if (!nd_region)
> return NULL;
> + nd_region->ndr_mappings = ndr_desc->num_mappings;
> /* CXL pre-assigns memregion ids before creating nvdimm regions */
> if (test_bit(ND_REGION_CXL, &ndr_desc->flags)) {
> nd_region->id = ndr_desc->memregion;
> @@ -1062,7 +1063,6 @@ static struct nd_region *nd_region_create(struct
> nvdimm_bus *nvdimm_bus,
>
> get_device(&nvdimm->dev);
> }
> - nd_region->ndr_mappings = ndr_desc->num_mappings;
> nd_region->provider_data = ndr_desc->provider_data;
> nd_region->nd_set = ndr_desc->nd_set;
> nd_region->num_lanes = ndr_desc->num_lanes;
