Message-ID: <CACT4Y+baAj7jgmFeudX2tP=tPan5vtOY7dE2anLgRFKS3Hb2Jw@mail.gmail.com>
Date: Thu, 4 Jul 2024 17:10:03 +0200
From: Dmitry Vyukov <dvyukov@...gle.com>
To: syzbot <syzbot+113b65786d8662e21ff7@...kaller.appspotmail.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] KCSAN: data-race in __dev_change_flags /
 is_upper_ndev_bond_master_filter (9)

On Thu, 4 Jul 2024 at 17:07, syzbot
<syzbot+113b65786d8662e21ff7@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    8a9c6c40432e Merge tag 'io_uring-6.10-20240703' of git://g..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1558eeb9980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
> dashboard link: https://syzkaller.appspot.com/bug?extid=113b65786d8662e21ff7
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f01153f3ec8e/disk-8a9c6c40.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/04b88663a824/vmlinux-8a9c6c40.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/63c518cc63c5/bzImage-8a9c6c40.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+113b65786d8662e21ff7@...kaller.appspotmail.com
>
> ==================================================================
> BUG: KCSAN: data-race in __dev_change_flags / is_upper_ndev_bond_master_filter
>
> read-write to 0xffff888112fca0b0 of 4 bytes by task 9257 on cpu 1:
>  __dev_change_flags+0x9a/0x410 net/core/dev.c:8755

This:

dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
      IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
      IFF_AUTOMEDIA)) |
    (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
   IFF_ALLMULTI));

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/core/dev.c?id=8a9c6c40432e265600232b864f97d7c675e8be52#n8755

lots of potential to be compiled in a way that temporarily exposes
dev->flags as not having the first or the second part of flags, even
though these flags are supposed to be set before and after the
operation.

I guess randomly missing flags can lead to arbitrary bugs elsewhere.


>  rtnl_configure_link net/core/rtnetlink.c:3321 [inline]
>  rtnl_newlink_create net/core/rtnetlink.c:3518 [inline]
>  __rtnl_newlink net/core/rtnetlink.c:3730 [inline]
>  rtnl_newlink+0x121e/0x1690 net/core/rtnetlink.c:3743
>  rtnetlink_rcv_msg+0x85e/0x910 net/core/rtnetlink.c:6635
>  netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2564
>  rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6653
>  netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
>  netlink_unicast+0x58d/0x660 net/netlink/af_netlink.c:1361
>  netlink_sendmsg+0x5ca/0x6e0 net/netlink/af_netlink.c:1905
>  sock_sendmsg_nosec net/socket.c:730 [inline]
>  __sock_sendmsg+0x140/0x180 net/socket.c:745
>  ____sys_sendmsg+0x312/0x410 net/socket.c:2585
>  ___sys_sendmsg net/socket.c:2639 [inline]
>  __sys_sendmsg+0x1e9/0x280 net/socket.c:2668
>  __do_sys_sendmsg net/socket.c:2677 [inline]
>  __se_sys_sendmsg net/socket.c:2675 [inline]
>  __x64_sys_sendmsg+0x46/0x50 net/socket.c:2675
>  x64_sys_call+0xb25/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:47
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> read to 0xffff888112fca0b0 of 4 bytes by task 3104 on cpu 0:
>  netif_is_bond_master include/linux/netdevice.h:5020 [inline]
>  is_upper_ndev_bond_master_filter+0x2b/0xb0 drivers/infiniband/core/roce_gid_mgmt.c:275
>  ib_enum_roce_netdev+0x124/0x1d0 drivers/infiniband/core/device.c:2310
>  ib_enum_all_roce_netdevs+0x8a/0x100 drivers/infiniband/core/device.c:2337
>  netdevice_event_work_handler+0x15b/0x3c0 drivers/infiniband/core/roce_gid_mgmt.c:626
>  process_one_work kernel/workqueue.c:3248 [inline]
>  process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3329
>  worker_thread+0x526/0x720 kernel/workqueue.c:3409
>  kthread+0x1d1/0x210 kernel/kthread.c:389
>  ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>
> value changed: 0x00001002 -> 0x00008002
>
> Reported by Kernel Concurrency Sanitizer on:
> CPU: 0 PID: 3104 Comm: kworker/u8:6 Not tainted 6.10.0-rc6-syzkaller-00067-g8a9c6c40432e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
> Workqueue: gid-cache-wq netdevice_event_work_handler
> ==================================================================
> netdevsim netdevsim3 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
> netdevsim netdevsim3 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
> netdevsim netdevsim3 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
> netdevsim netdevsim3 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
> bridge_slave_1: left allmulticast mode
> bridge_slave_1: left promiscuous mode
> bridge0: port 2(bridge_slave_1) entered disabled state
> bridge_slave_0: left allmulticast mode
> bridge_slave_0: left promiscuous mode
> bridge0: port 1(bridge_slave_0) entered disabled state
> bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
> bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
> bond0 (unregistering): Released all slaves
> hsr_slave_0: left promiscuous mode
> hsr_slave_1: left promiscuous mode
> batman_adv: batadv0: Interface deactivated: batadv_slave_0
> batman_adv: batadv0: Removing interface: batadv_slave_0
> batman_adv: batadv0: Interface deactivated: batadv_slave_1
> batman_adv: batadv0: Removing interface: batadv_slave_1
> veth1_macvtap: left promiscuous mode
> veth0_macvtap: left promiscuous mode
> veth1_vlan: left promiscuous mode
> veth0_vlan: left promiscuous mode
> team0 (unregistering): Port device team_slave_1 removed
> team0 (unregistering): Port device team_slave_0 removed
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
>
> syzbot will keep track of this issue. See:
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>
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