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Message-ID: <baa1f1e8-7fa6-fadf-584f-71f9d0b3dcdb@gmail.com> Date: Sat, 13 Jan 2024 01:16:23 +0900 From: Taehee Yoo <ap420073@...il.com> To: Eric Dumazet <edumazet@...gle.com>, syzbot <syzbot+a9400cabb1d784e49abf@...kaller.appspotmail.com> Cc: davem@...emloft.net, dsahern@...nel.org, 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 ipv6_mc_down / mld_ifc_work (2) On 1/12/24 21:01, Eric Dumazet wrote: Hi Eric, Thank you for the report! > On Fri, Jan 12, 2024 at 11:10 AM syzbot > <syzbot+a9400cabb1d784e49abf@...kaller.appspotmail.com> wrote: >> >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 8735c7c84d1b Merge tag '6.7rc7-smb3-srv-fix' of git://git... >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=17948c9ae80000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=4da1e2da456c3a7d >> dashboard link: https://syzkaller.appspot.com/bug?extid=a9400cabb1d784e49abf >> 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/f263d974af01/disk-8735c7c8.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/9faf34fc0b3e/vmlinux-8735c7c8.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/0b52a58ecd0e/bzImage-8735c7c8.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+a9400cabb1d784e49abf@...kaller.appspotmail.com >> >> ================================================================== >> BUG: KCSAN: data-race in ipv6_mc_down / mld_ifc_work >> >> write to 0xffff88813a80c832 of 1 bytes by task 3771 on cpu 0: >> mld_ifc_stop_work net/ipv6/mcast.c:1080 [inline] >> ipv6_mc_down+0x10a/0x280 net/ipv6/mcast.c:2725 >> addrconf_ifdown+0xe32/0xf10 net/ipv6/addrconf.c:3949 >> addrconf_notify+0x310/0x980 >> notifier_call_chain kernel/notifier.c:93 [inline] >> raw_notifier_call_chain+0x6b/0x1c0 kernel/notifier.c:461 >> __dev_notify_flags+0x205/0x3d0 >> dev_change_flags+0xab/0xd0 net/core/dev.c:8685 >> do_setlink+0x9f6/0x2430 net/core/rtnetlink.c:2916 >> rtnl_group_changelink net/core/rtnetlink.c:3458 [inline] >> __rtnl_newlink net/core/rtnetlink.c:3717 [inline] >> rtnl_newlink+0xbb3/0x1670 net/core/rtnetlink.c:3754 >> rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6558 >> netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2545 >> rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6576 >> netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline] >> netlink_unicast+0x589/0x650 net/netlink/af_netlink.c:1368 >> netlink_sendmsg+0x66e/0x770 net/netlink/af_netlink.c:1910 >> sock_sendmsg_nosec net/socket.c:730 [inline] >> __sock_sendmsg net/socket.c:745 [inline] >> ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2584 >> ___sys_sendmsg net/socket.c:2638 [inline] >> __sys_sendmsg+0x1e9/0x270 net/socket.c:2667 >> __do_sys_sendmsg net/socket.c:2676 [inline] >> __se_sys_sendmsg net/socket.c:2674 [inline] >> __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674 >> do_syscall_x64 arch/x86/entry/common.c:52 [inline] >> do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 >> entry_SYSCALL_64_after_hwframe+0x63/0x6b >> >> write to 0xffff88813a80c832 of 1 bytes by task 22 on cpu 1: >> mld_ifc_work+0x54c/0x7b0 net/ipv6/mcast.c:2653 >> process_one_work kernel/workqueue.c:2627 [inline] >> process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2700 >> worker_thread+0x525/0x730 kernel/workqueue.c:2781 >> kthread+0x1d7/0x210 kernel/kthread.c:388 >> ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147 >> ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 >> >> value changed: 0x02 -> 0x00 >> >> Reported by Kernel Concurrency Sanitizer on: >> CPU: 1 PID: 22 Comm: kworker/1:0 Not tainted 6.7.0-rc7-syzkaller-00029-g8735c7c84d1b #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 >> Workqueue: mld mld_ifc_work >> ================================================================== >> >> >> --- >> 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: >> https://goo.gl/tpsmEJ#status for how to communicate with syzbot. >> >> If the report is already addressed, let syzbot know by replying with: >> #syz fix: exact-commit-title >> >> If you want to overwrite report's subsystems, reply with: >> #syz set subsystems: new-subsystem >> (See the list of subsystem names on the web dashboard) >> >> If the report is a duplicate of another one, reply with: >> #syz dup: exact-subject-of-another-report >> >> If you want to undo deduplication, reply with: >> #syz undup > > Bug added in > > commit 63ed8de4be81b699ca727e9f8e3344bd487806d7 > Author: Taehee Yoo <ap420073@...il.com> > Date: Thu Mar 25 16:16:57 2021 +0000 > > mld: add mc_lock for protecting per-interface mld data > > > ipv6_mc_down() calls mld_ifc_stop_work() while mc_lock is not held. Thanks a lot for the analysis, I will look into this. Thanks a lot! Taehee Yoo
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