slave->last_rx and slave->target_last_arp_rx[...] can be read and written locklessly. Add READ_ONCE() and WRITE_ONCE() annotations. syzbot reported: BUG: KCSAN: data-race in bond_rcv_validate / bond_rcv_validate write to 0xffff888149f0d428 of 8 bytes by interrupt on cpu 1: bond_rcv_validate+0x202/0x7a0 drivers/net/bonding/bond_main.c:3335 bond_handle_frame+0xde/0x5e0 drivers/net/bonding/bond_main.c:1533 __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6039 __netif_receive_skb_one_core net/core/dev.c:6150 [inline] __netif_receive_skb+0x59/0x270 net/core/dev.c:6265 netif_receive_skb_internal net/core/dev.c:6351 [inline] netif_receive_skb+0x4b/0x2d0 net/core/dev.c:6410 ... write to 0xffff888149f0d428 of 8 bytes by interrupt on cpu 0: bond_rcv_validate+0x202/0x7a0 drivers/net/bonding/bond_main.c:3335 bond_handle_frame+0xde/0x5e0 drivers/net/bonding/bond_main.c:1533 __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6039 __netif_receive_skb_one_core net/core/dev.c:6150 [inline] __netif_receive_skb+0x59/0x270 net/core/dev.c:6265 netif_receive_skb_internal net/core/dev.c:6351 [inline] netif_receive_skb+0x4b/0x2d0 net/core/dev.c:6410 br_netif_receive_skb net/bridge/br_input.c:30 [inline] NF_HOOK include/linux/netfilter.h:318 [inline] ... value changed: 0x0000000100005365 -> 0x0000000100005366 Fixes: f5b2b966f032 ("[PATCH] bonding: Validate probe replies in ARP monitor") Signed-off-by: Eric Dumazet Reported-by: syzbot --- v2: Addressed AI feedback about _bond_options_ns_ip6_target_set() Added {READ,WRITEE_ONCE() in bond_option_arp_ip_target_rem() v1: https://lore.kernel.org/netdev/20260120152856.1694824-1-edumazet@google.com/ drivers/net/bonding/bond_main.c | 18 ++++++++++-------- drivers/net/bonding/bond_options.c | 8 ++++---- include/net/bonding.h | 13 +++++++------ 3 files changed, 21 insertions(+), 18 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index e7caf400a59cbd9680adea3d1b8ab7a22c78f7e6..a909ebcf1102d46beadc216a1b1a8a10e227ecb4 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3047,8 +3047,8 @@ static void bond_validate_arp(struct bonding *bond, struct slave *slave, __be32 __func__, &sip); return; } - slave->last_rx = jiffies; - slave->target_last_arp_rx[i] = jiffies; + WRITE_ONCE(slave->last_rx, jiffies); + WRITE_ONCE(slave->target_last_arp_rx[i], jiffies); } static int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, @@ -3267,8 +3267,8 @@ static void bond_validate_na(struct bonding *bond, struct slave *slave, __func__, saddr); return; } - slave->last_rx = jiffies; - slave->target_last_arp_rx[i] = jiffies; + WRITE_ONCE(slave->last_rx, jiffies); + WRITE_ONCE(slave->target_last_arp_rx[i], jiffies); } static int bond_na_rcv(const struct sk_buff *skb, struct bonding *bond, @@ -3338,7 +3338,7 @@ int bond_rcv_validate(const struct sk_buff *skb, struct bonding *bond, (slave_do_arp_validate_only(bond) && is_ipv6) || #endif !slave_do_arp_validate_only(bond)) - slave->last_rx = jiffies; + WRITE_ONCE(slave->last_rx, jiffies); return RX_HANDLER_ANOTHER; } else if (is_arp) { return bond_arp_rcv(skb, bond, slave); @@ -3406,7 +3406,7 @@ static void bond_loadbalance_arp_mon(struct bonding *bond) if (slave->link != BOND_LINK_UP) { if (bond_time_in_interval(bond, last_tx, 1) && - bond_time_in_interval(bond, slave->last_rx, 1)) { + bond_time_in_interval(bond, READ_ONCE(slave->last_rx), 1)) { bond_propose_link_state(slave, BOND_LINK_UP); slave_state_changed = 1; @@ -3430,8 +3430,10 @@ static void bond_loadbalance_arp_mon(struct bonding *bond) * when the source ip is 0, so don't take the link down * if we don't know our ip yet */ - if (!bond_time_in_interval(bond, last_tx, bond->params.missed_max) || - !bond_time_in_interval(bond, slave->last_rx, bond->params.missed_max)) { + if (!bond_time_in_interval(bond, last_tx, + bond->params.missed_max) || + !bond_time_in_interval(bond, READ_ONCE(slave->last_rx), + bond->params.missed_max)) { bond_propose_link_state(slave, BOND_LINK_DOWN); slave_state_changed = 1; diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c index 384499c869b8da9f036c43eb081095f1bf2141af..f1c6e9d8f61671e817bb417af39271dc14dd7bd9 100644 --- a/drivers/net/bonding/bond_options.c +++ b/drivers/net/bonding/bond_options.c @@ -1152,7 +1152,7 @@ static void _bond_options_arp_ip_target_set(struct bonding *bond, int slot, if (slot >= 0 && slot < BOND_MAX_ARP_TARGETS) { bond_for_each_slave(bond, slave, iter) - slave->target_last_arp_rx[slot] = last_rx; + WRITE_ONCE(slave->target_last_arp_rx[slot], last_rx); targets[slot] = target; } } @@ -1221,8 +1221,8 @@ static int bond_option_arp_ip_target_rem(struct bonding *bond, __be32 target) bond_for_each_slave(bond, slave, iter) { targets_rx = slave->target_last_arp_rx; for (i = ind; (i < BOND_MAX_ARP_TARGETS-1) && targets[i+1]; i++) - targets_rx[i] = targets_rx[i+1]; - targets_rx[i] = 0; + WRITE_ONCE(targets_rx[i], READ_ONCE(targets_rx[i+1])); + WRITE_ONCE(targets_rx[i], 0); } for (i = ind; (i < BOND_MAX_ARP_TARGETS-1) && targets[i+1]; i++) targets[i] = targets[i+1]; @@ -1377,7 +1377,7 @@ static void _bond_options_ns_ip6_target_set(struct bonding *bond, int slot, if (slot >= 0 && slot < BOND_MAX_NS_TARGETS) { bond_for_each_slave(bond, slave, iter) { - slave->target_last_arp_rx[slot] = last_rx; + WRITE_ONCE(slave->target_last_arp_rx[slot], last_rx); slave_set_ns_maddr(bond, slave, target, &targets[slot]); } targets[slot] = *target; diff --git a/include/net/bonding.h b/include/net/bonding.h index 49edc7da05867f355f880329817bdc2a371f226b..46207840355709ee28d771c803b8ee6ef8920538 100644 --- a/include/net/bonding.h +++ b/include/net/bonding.h @@ -521,13 +521,14 @@ static inline int bond_is_ip6_target_ok(struct in6_addr *addr) static inline unsigned long slave_oldest_target_arp_rx(struct bonding *bond, struct slave *slave) { + unsigned long tmp, ret = READ_ONCE(slave->target_last_arp_rx[0]); int i = 1; - unsigned long ret = slave->target_last_arp_rx[0]; - - for (; (i < BOND_MAX_ARP_TARGETS) && bond->params.arp_targets[i]; i++) - if (time_before(slave->target_last_arp_rx[i], ret)) - ret = slave->target_last_arp_rx[i]; + for (; (i < BOND_MAX_ARP_TARGETS) && bond->params.arp_targets[i]; i++) { + tmp = READ_ONCE(slave->target_last_arp_rx[i]); + if (time_before(tmp, ret)) + ret = tmp; + } return ret; } @@ -537,7 +538,7 @@ static inline unsigned long slave_last_rx(struct bonding *bond, if (bond->params.arp_all_targets == BOND_ARP_TARGETS_ALL) return slave_oldest_target_arp_rx(bond, slave); - return slave->last_rx; + return READ_ONCE(slave->last_rx); } static inline void slave_update_last_tx(struct slave *slave) -- 2.52.0.457.g6b5491de43-goog