From: Eric Dumazet edumazet@google.com
[ Upstream commit 6ebfad33161afacb3e1e59ed1c2feefef70f9f97 ]
ignore_outgoing is read locklessly from dev_queue_xmit_nit() and packet_getsockopt()
Add appropriate READ_ONCE()/WRITE_ONCE() annotations.
syzbot reported:
BUG: KCSAN: data-race in dev_queue_xmit_nit / packet_setsockopt
write to 0xffff888107804542 of 1 bytes by task 22618 on cpu 0: packet_setsockopt+0xd83/0xfd0 net/packet/af_packet.c:4003 do_sock_setsockopt net/socket.c:2311 [inline] __sys_setsockopt+0x1d8/0x250 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340 do_syscall_64+0xd3/0x1d0 entry_SYSCALL_64_after_hwframe+0x6d/0x75
read to 0xffff888107804542 of 1 bytes by task 27 on cpu 1: dev_queue_xmit_nit+0x82/0x620 net/core/dev.c:2248 xmit_one net/core/dev.c:3527 [inline] dev_hard_start_xmit+0xcc/0x3f0 net/core/dev.c:3547 __dev_queue_xmit+0xf24/0x1dd0 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3091 [inline] batadv_send_skb_packet+0x264/0x300 net/batman-adv/send.c:108 batadv_send_broadcast_skb+0x24/0x30 net/batman-adv/send.c:127 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x3f0/0x4b0 net/batman-adv/bat_iv_ogm.c:1700 process_one_work kernel/workqueue.c:3254 [inline] process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335 worker_thread+0x526/0x730 kernel/workqueue.c:3416 kthread+0x1d1/0x210 kernel/kthread.c:388 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
value changed: 0x00 -> 0x01
Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 27 Comm: kworker/u8:1 Tainted: G W 6.8.0-syzkaller-08073-g480e035fc4c7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Fixes: fa788d986a3a ("packet: add sockopt to ignore outgoing packets") Reported-by: syzbot+c669c1136495a2e7c31f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/CANn89i+Z7MfbkBLOv=p7KZ7=K1rKHO4P1OL5LYDCtBiy... Signed-off-by: Eric Dumazet edumazet@google.com Cc: Willem de Bruijn willemdebruijn.kernel@gmail.com Reviewed-by: Willem de Bruijn willemb@google.com Reviewed-by: Jason Xing kerneljasonxing@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/dev.c | 2 +- net/packet/af_packet.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c index 5e043e6f09476..4f39d97209811 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1940,7 +1940,7 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev) rcu_read_lock(); again: list_for_each_entry_rcu(ptype, ptype_list, list) { - if (ptype->ignore_outgoing) + if (READ_ONCE(ptype->ignore_outgoing)) continue;
/* Never send packets back to the socket diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 451f9c43b34b8..9fc020fd7ecc1 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3921,7 +3921,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv if (val < 0 || val > 1) return -EINVAL;
- po->prot_hook.ignore_outgoing = !!val; + WRITE_ONCE(po->prot_hook.ignore_outgoing, !!val); return 0; } case PACKET_TX_HAS_OFF: @@ -4053,7 +4053,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, 0); break; case PACKET_IGNORE_OUTGOING: - val = po->prot_hook.ignore_outgoing; + val = READ_ONCE(po->prot_hook.ignore_outgoing); break; case PACKET_ROLLOVER_STATS: if (!po->rollover)