On 27/10/2021 16:49, Ivan Vecera wrote:
> Function br_get_link_af_size_filtered() calls br_cfm_{,peer}_mep_count()
> but does not check their return value. When BRIDGE_CFM is not enabled
> these functions return -EOPNOTSUPP but do not modify count parameter.
> Calling function then works with uninitialized variables.
>
> Fixes: b6d0425b816e ("bridge: cfm: Netlink Notifications.")
> Signed-off-by: Ivan Vecera <ivecera@xxxxxxxxxx>
> ---
> net/bridge/br_netlink.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index 5c6c4305ed23..12d602495ea0 100644
> --- a/net/bridge/br_netlink.c
> +++ b/net/bridge/br_netlink.c
> @@ -126,8 +126,10 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev,
> return vinfo_sz;
>
> /* CFM status info must be added */
> - br_cfm_mep_count(br, &num_cfm_mep_infos);
> - br_cfm_peer_mep_count(br, &num_cfm_peer_mep_infos);
> + if (br_cfm_mep_count(br, &num_cfm_mep_infos) < 0)
> + num_cfm_mep_infos = 0;
> + if (br_cfm_peer_mep_count(br, &num_cfm_peer_mep_infos) < 0)
> + num_cfm_peer_mep_infos = 0;
>
> vinfo_sz += nla_total_size(0); /* IFLA_BRIDGE_CFM */
> /* For each status struct the MEP instance (u32) is added */
>
Hi,
Could you please rather update the EOPNOTSUPP helpers to set these infos to 0 before
returning? Someone else might decide to use them and hit the same bug.
E.g.
static inline int br_cfm_mep_count(struct net_bridge *br, u32 *count)
{
*count = 0;
return -EOPNOTSUPP;
}
We already do the same for br_allowed_ingress, nbp_vlan_add() etc.
Thanks,
Nik
