Skip to content

Commit

Permalink
packet: annotate data-races around ignore_outgoing
Browse files Browse the repository at this point in the history
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: [email protected]
Closes: https://lore.kernel.org/netdev/CANn89i+Z7MfbkBLOv=p7KZ7=K1rKHO4P1OL5LYDCtBiyqsa9oQ@mail.gmail.com/T/#t
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Reviewed-by: Jason Xing <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
  • Loading branch information
Eric Dumazet authored and davem330 committed Mar 18, 2024
1 parent badc9e3 commit 6ebfad3
Show file tree
Hide file tree
Showing 2 changed files with 3 additions and 3 deletions.
2 changes: 1 addition & 1 deletion net/core/dev.c
Original file line number Diff line number Diff line change
Expand Up @@ -2245,7 +2245,7 @@ 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
Expand Down
4 changes: 2 additions & 2 deletions net/packet/af_packet.c
Original file line number Diff line number Diff line change
Expand Up @@ -4000,7 +4000,7 @@ 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:
Expand Down Expand Up @@ -4134,7 +4134,7 @@ 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)
Expand Down

0 comments on commit 6ebfad3

Please sign in to comment.