packet: annotate data-races around ignore_outgoing

[ 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: fa788d9 ("packet: add sockopt to ignore outgoing packets") Reported-by: syzbot+c669c1136495a2e7c31f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/CANn89i+Z7MfbkBLOv=p7KZ7=K1rKHO4P1OL5LYDCtBiyqsa9oQ@mail.gmail.com/T/#t 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>
xanmod · Mar 26, 2024 · 2c02c50 · 2c02c50
1 parent cfbb3ab
commit 2c02c50
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Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/net/core/dev.c b/net/core/dev.c
@@ -2290,7 +2290,7 @@ 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
@@ -4004,7 +4004,7 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
 		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:
@@ -4135,7 +4135,7 @@ 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)