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SubjectRe: [PATCH] mlxsw: core_acl_flex_actions: Split memcpy() of struct flow_action_cookie flexible array
On Mon, Sep 26, 2022 at 05:40:33PM -0700, Kees Cook wrote:
> To work around a misbehavior of the compiler's ability to see into
> composite flexible array structs (as detailed in the coming memcpy()
> hardening series[1]), split the memcpy() of the header and the payload
> so no false positive run-time overflow warning will be generated.
>
> [1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keescook@chromium.org
>
> Cc: Ido Schimmel <idosch@nvidia.com>
> Cc: Petr Machata <petrm@nvidia.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>


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

Thanks!
--
Gustavo

> ---
> drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
> index 636db9a87457..9dfe7148199f 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
> @@ -737,8 +737,9 @@ mlxsw_afa_cookie_create(struct mlxsw_afa *mlxsw_afa,
> if (!cookie)
> return ERR_PTR(-ENOMEM);
> refcount_set(&cookie->ref_count, 1);
> - memcpy(&cookie->fa_cookie, fa_cookie,
> - sizeof(*fa_cookie) + fa_cookie->cookie_len);
> + cookie->fa_cookie = *fa_cookie;
> + memcpy(cookie->fa_cookie.cookie, fa_cookie->cookie,
> + fa_cookie->cookie_len);
>
> err = rhashtable_insert_fast(&mlxsw_afa->cookie_ht, &cookie->ht_node,
> mlxsw_afa_cookie_ht_params);
> --
> 2.34.1
>

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