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Subject[PATCH] mlxsw: core_acl_flex_actions: Split memcpy() of struct flow_action_cookie flexible array
Date
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>
---
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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