From: Eric Dumazet edumazet@google.com
commit 9ceaf6f76b203682bb6100e14b3d7da4c0bedde8 upstream.
syzbot reported that two threads might write over agg_select_timer at the same time. Make agg_select_timer atomic to fix the races.
BUG: KCSAN: data-race in bond_3ad_initiate_agg_selection / bond_3ad_state_machine_handler
read to 0xffff8881242aea90 of 4 bytes by task 1846 on cpu 1: bond_3ad_state_machine_handler+0x99/0x2810 drivers/net/bonding/bond_3ad.c:2317 process_one_work+0x3f6/0x960 kernel/workqueue.c:2307 worker_thread+0x616/0xa70 kernel/workqueue.c:2454 kthread+0x1bf/0x1e0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30
write to 0xffff8881242aea90 of 4 bytes by task 25910 on cpu 0: bond_3ad_initiate_agg_selection+0x18/0x30 drivers/net/bonding/bond_3ad.c:1998 bond_open+0x658/0x6f0 drivers/net/bonding/bond_main.c:3967 __dev_open+0x274/0x3a0 net/core/dev.c:1407 dev_open+0x54/0x190 net/core/dev.c:1443 bond_enslave+0xcef/0x3000 drivers/net/bonding/bond_main.c:1937 do_set_master net/core/rtnetlink.c:2532 [inline] do_setlink+0x94f/0x2500 net/core/rtnetlink.c:2736 __rtnl_newlink net/core/rtnetlink.c:3414 [inline] rtnl_newlink+0xfeb/0x13e0 net/core/rtnetlink.c:3529 rtnetlink_rcv_msg+0x745/0x7e0 net/core/rtnetlink.c:5594 netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2494 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5612 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x602/0x6d0 net/netlink/af_netlink.c:1343 netlink_sendmsg+0x728/0x850 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg net/socket.c:725 [inline] ____sys_sendmsg+0x39a/0x510 net/socket.c:2413 ___sys_sendmsg net/socket.c:2467 [inline] __sys_sendmsg+0x195/0x230 net/socket.c:2496 __do_sys_sendmsg net/socket.c:2505 [inline] __se_sys_sendmsg net/socket.c:2503 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2503 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae
value changed: 0x00000050 -> 0x0000004f
Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 25910 Comm: syz-executor.1 Tainted: G W 5.17.0-rc4-syzkaller-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Cc: Jay Vosburgh j.vosburgh@gmail.com Cc: Veaceslav Falico vfalico@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/bonding/bond_3ad.c | 30 +++++++++++++++++++++++++----- include/net/bond_3ad.h | 2 +- 2 files changed, 26 insertions(+), 6 deletions(-)
--- a/drivers/net/bonding/bond_3ad.c +++ b/drivers/net/bonding/bond_3ad.c @@ -223,7 +223,7 @@ static inline int __check_agg_selection_ if (bond == NULL) return 0;
- return BOND_AD_INFO(bond).agg_select_timer ? 1 : 0; + return atomic_read(&BOND_AD_INFO(bond).agg_select_timer) ? 1 : 0; }
/** @@ -1976,7 +1976,7 @@ static void ad_marker_response_received( */ void bond_3ad_initiate_agg_selection(struct bonding *bond, int timeout) { - BOND_AD_INFO(bond).agg_select_timer = timeout; + atomic_set(&BOND_AD_INFO(bond).agg_select_timer, timeout); }
/** @@ -2260,6 +2260,28 @@ void bond_3ad_update_ad_actor_settings(s }
/** + * bond_agg_timer_advance - advance agg_select_timer + * @bond: bonding structure + * + * Return true when agg_select_timer reaches 0. + */ +static bool bond_agg_timer_advance(struct bonding *bond) +{ + int val, nval; + + while (1) { + val = atomic_read(&BOND_AD_INFO(bond).agg_select_timer); + if (!val) + return false; + nval = val - 1; + if (atomic_cmpxchg(&BOND_AD_INFO(bond).agg_select_timer, + val, nval) == val) + break; + } + return nval == 0; +} + +/** * bond_3ad_state_machine_handler - handle state machines timeout * @work: work context to fetch bonding struct to work on from * @@ -2294,9 +2316,7 @@ void bond_3ad_state_machine_handler(stru if (!bond_has_slaves(bond)) goto re_arm;
- /* check if agg_select_timer timer after initialize is timed out */ - if (BOND_AD_INFO(bond).agg_select_timer && - !(--BOND_AD_INFO(bond).agg_select_timer)) { + if (bond_agg_timer_advance(bond)) { slave = bond_first_slave_rcu(bond); port = slave ? &(SLAVE_AD_INFO(slave)->port) : NULL;
--- a/include/net/bond_3ad.h +++ b/include/net/bond_3ad.h @@ -262,7 +262,7 @@ struct ad_system { struct ad_bond_info { struct ad_system system; /* 802.3ad system structure */ struct bond_3ad_stats stats; - u32 agg_select_timer; /* Timer to select aggregator after all adapter's hand shakes */ + atomic_t agg_select_timer; /* Timer to select aggregator after all adapter's hand shakes */ u16 aggregator_identifier; };