diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h index d696f9e414e3..d97d03f4d31b 100644 --- a/net/tipc/bearer.h +++ b/net/tipc/bearer.h @@ -47,6 +47,13 @@ */ #define TIPC_MEDIA_TYPE_ETH 1 +/* Message header sizes from msg.h - duplicated to avoid mutual inclusion */ +#define INT_H_SIZE 40 +#define MAX_H_SIZE 60 + +/* minimum bearer MTU */ +#define TIPC_MIN_BEARER_MTU (MAX_H_SIZE + INT_H_SIZE) + /* * Destination address structure used by TIPC bearers when sending messages * @@ -209,4 +216,13 @@ static inline int tipc_bearer_send(struct tipc_bearer *b_ptr, return !b_ptr->media->send_msg(buf, b_ptr, dest); } +/* check if device MTU is too low for tipc headers */ +static inline bool tipc_mtu_bad(struct net_device *dev, unsigned int reserve) +{ + if (dev->mtu >= TIPC_MIN_BEARER_MTU + reserve) + return false; + netdev_warn(dev, "MTU too low for tipc bearer\n"); + return true; +} + #endif /* _TIPC_BEARER_H */ diff --git a/net/tipc/eth_media.c b/net/tipc/eth_media.c index a224a38f0218..2e79e84660fb 100644 --- a/net/tipc/eth_media.c +++ b/net/tipc/eth_media.c @@ -167,6 +167,10 @@ static int enable_bearer(struct tipc_bearer *tb_ptr) read_unlock(&dev_base_lock); if (!dev) return -ENODEV; + if (tipc_mtu_bad(dev, 0)) { + dev_put(dev); + return -EINVAL; + } /* Create Ethernet bearer for device */ @@ -227,8 +231,6 @@ static int recv_notification(struct notifier_block *nb, unsigned long evt, if (!eb_ptr->bearer) return NOTIFY_DONE; /* bearer had been disabled */ - eb_ptr->bearer->mtu = dev->mtu; - switch (evt) { case NETDEV_CHANGE: if (netif_carrier_ok(dev)) @@ -243,6 +245,12 @@ static int recv_notification(struct notifier_block *nb, unsigned long evt, tipc_block_bearer(eb_ptr->bearer->name); break; case NETDEV_CHANGEMTU: + if (tipc_mtu_bad(dev, 0)) { + tipc_disable_bearer(eb_ptr->bearer->name); + break; + } + eb_ptr->bearer->mtu = dev->mtu; + /* fall through */ case NETDEV_CHANGEADDR: tipc_block_bearer(eb_ptr->bearer->name); tipc_continue(eb_ptr->bearer);