As reported[1] if query interval is set too low and we have multiple bridges or even a single bridge with multiple querier vlans configured we can crash the machine. Add a 1 second minimum which must be enforced by overwriting the value if set lower (i.e. without returning an error) to avoid breaking user-space. If that happens a log message is emitted to let the administrator know that the interval has been set to the minimum. The issue has been present since these intervals could be user-controlled.
[1] https://lore.kernel.org/netdev/[email protected]/ Fixes: d902eee43f19 ("bridge: Add multicast count/interval sysfs entries") Reported-by: Eric Dumazet <[email protected]> Signed-off-by: Nikolay Aleksandrov <[email protected]> --- net/bridge/br_multicast.c | 16 ++++++++++++++++ net/bridge/br_netlink.c | 2 +- net/bridge/br_private.h | 3 +++ net/bridge/br_sysfs_br.c | 2 +- net/bridge/br_vlan_options.c | 2 +- 5 files changed, 22 insertions(+), 3 deletions(-) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index f3d751105343..998da4a2d209 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4522,6 +4522,22 @@ int br_multicast_set_mld_version(struct net_bridge_mcast *brmctx, } #endif +void br_multicast_set_query_intvl(struct net_bridge_mcast *brmctx, + unsigned long val) +{ + unsigned long intvl_jiffies = clock_t_to_jiffies(val); + + if (intvl_jiffies < BR_MULTICAST_QUERY_INTVL_MIN) { + br_info(brmctx->br, + "trying to set multicast query interval below minimum, setting to %lu (%ums)\n", + jiffies_to_clock_t(BR_MULTICAST_QUERY_INTVL_MIN), + jiffies_to_msecs(BR_MULTICAST_QUERY_INTVL_MIN)); + intvl_jiffies = BR_MULTICAST_QUERY_INTVL_MIN; + } + + brmctx->multicast_query_interval = intvl_jiffies; +} + /** * br_multicast_list_adjacent - Returns snooped multicast addresses * @dev: The bridge port adjacent to which to retrieve addresses diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c index 0c8b5f1a15bc..701dd8b8455e 100644 --- a/net/bridge/br_netlink.c +++ b/net/bridge/br_netlink.c @@ -1357,7 +1357,7 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[], if (data[IFLA_BR_MCAST_QUERY_INTVL]) { u64 val = nla_get_u64(data[IFLA_BR_MCAST_QUERY_INTVL]); - br->multicast_ctx.multicast_query_interval = clock_t_to_jiffies(val); + br_multicast_set_query_intvl(&br->multicast_ctx, val); } if (data[IFLA_BR_MCAST_QUERY_RESPONSE_INTVL]) { diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index c0efd697865a..4ed7f11042e8 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -28,6 +28,7 @@ #define BR_MAX_PORTS (1<<BR_PORT_BITS) #define BR_MULTICAST_DEFAULT_HASH_MAX 4096 +#define BR_MULTICAST_QUERY_INTVL_MIN msecs_to_jiffies(1000) #define BR_HWDOM_MAX BITS_PER_LONG @@ -963,6 +964,8 @@ int br_multicast_dump_querier_state(struct sk_buff *skb, int nest_attr); size_t br_multicast_querier_state_size(void); size_t br_rports_size(const struct net_bridge_mcast *brmctx); +void br_multicast_set_query_intvl(struct net_bridge_mcast *brmctx, + unsigned long val); static inline bool br_group_is_l2(const struct br_ip *group) { diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c index d9a89ddd0331..f5bd1114a434 100644 --- a/net/bridge/br_sysfs_br.c +++ b/net/bridge/br_sysfs_br.c @@ -658,7 +658,7 @@ static ssize_t multicast_query_interval_show(struct device *d, static int set_query_interval(struct net_bridge *br, unsigned long val, struct netlink_ext_ack *extack) { - br->multicast_ctx.multicast_query_interval = clock_t_to_jiffies(val); + br_multicast_set_query_intvl(&br->multicast_ctx, val); return 0; } diff --git a/net/bridge/br_vlan_options.c b/net/bridge/br_vlan_options.c index 8ffd4ed2563c..bf1ac0874279 100644 --- a/net/bridge/br_vlan_options.c +++ b/net/bridge/br_vlan_options.c @@ -521,7 +521,7 @@ static int br_vlan_process_global_one_opts(const struct net_bridge *br, u64 val; val = nla_get_u64(tb[BRIDGE_VLANDB_GOPTS_MCAST_QUERY_INTVL]); - v->br_mcast_ctx.multicast_query_interval = clock_t_to_jiffies(val); + br_multicast_set_query_intvl(&v->br_mcast_ctx, val); *changed = true; } if (tb[BRIDGE_VLANDB_GOPTS_MCAST_QUERY_RESPONSE_INTVL]) { -- 2.33.1
