Re: WARNING: proc registration bug in snmp6_register_dev
syzbot has bisected this bug to:
commit e0a4b99773d3d8d3fb40087805f8fd858a23e582
Author: Taehee Yoo
Date: Fri Feb 28 18:02:10 2020 +
hsr: use upper/lower device infrastructure
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1481118210
start commit: ac935d22 Add linux-next specific files for 20200415
git tree: linux-next
final crash:https://syzkaller.appspot.com/x/report.txt?x=1681118210
console output: https://syzkaller.appspot.com/x/log.txt?x=1281118210
kernel config: https://syzkaller.appspot.com/x/.config?x=bc498783097e9019
dashboard link: https://syzkaller.appspot.com/bug?extid=1d51c8b74efa4c44adeb
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148e615010
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=115c379c10
Reported-by: syzbot+1d51c8b74efa4c44a...@syzkaller.appspotmail.com
Fixes: e0a4b99773d3 ("hsr: use upper/lower device infrastructure")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
Re: WARNING: proc registration bug in snmp6_register_dev
syzbot has found a reproducer for the following crash on: HEAD commit:ac935d22 Add linux-next specific files for 20200415 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=17006f4c10 kernel config: https://syzkaller.appspot.com/x/.config?x=bc498783097e9019 dashboard link: https://syzkaller.appspot.com/bug?extid=1d51c8b74efa4c44adeb compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148e615010 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=115c379c10 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+1d51c8b74efa4c44a...@syzkaller.appspotmail.com [ cut here ] proc_dir_entry 'dev_snmp6/hsr1' already registered WARNING: CPU: 0 PID: 7289 at fs/proc/generic.c:362 proc_register+0x40b/0x580 fs/proc/generic.c:362 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7289 Comm: syz-executor779 Not tainted 5.7.0-rc1-next-20200415-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 panic+0x2e3/0x75c kernel/panic.c:221 __warn.cold+0x2f/0x35 kernel/panic.c:582 report_bug+0x27b/0x2f0 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:175 [inline] fixup_bug arch/x86/kernel/traps.c:170 [inline] do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 RIP: 0010:proc_register+0x40b/0x580 fs/proc/generic.c:362 Code: ff df 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 5c 01 00 00 48 8b 04 24 48 c7 c7 a0 7a 39 88 48 8b b0 d8 00 00 00 e8 4d 2d 61 ff <0f> 0b 48 c7 c7 a0 ac ac 89 e8 f7 5b f3 05 48 8b 4c 24 28 48 b8 00 RSP: 0018:c90005956cc8 EFLAGS: 00010282 RAX: RBX: 8880a9138ac8 RCX: RDX: RSI: 815ce211 RDI: f52000b2ad8b RBP: 8880a1ab3a80 R08: 888087c40340 R09: ed1015cc66b1 R10: 8880ae633587 R11: ed1015cc66b0 R12: R13: dc00 R14: 8880a6561240 R15: 0004 proc_create_single_data+0xdb/0x130 fs/proc/generic.c:631 snmp6_register_dev+0xbe/0x140 net/ipv6/proc.c:254 ipv6_add_dev net/ipv6/addrconf.c:408 [inline] ipv6_add_dev+0x54b/0x10b0 net/ipv6/addrconf.c:365 addrconf_notify+0x960/0x2310 net/ipv6/addrconf.c:3503 notifier_call_chain+0xc0/0x230 kernel/notifier.c:83 call_netdevice_notifiers_info net/core/dev.c:1948 [inline] call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1933 call_netdevice_notifiers_extack net/core/dev.c:1960 [inline] call_netdevice_notifiers net/core/dev.c:1974 [inline] register_netdevice+0xd70/0x10b0 net/core/dev.c:9423 hsr_dev_finalize+0x516/0x746 net/hsr/hsr_device.c:486 hsr_newlink+0x27c/0x520 net/hsr/hsr_netlink.c:83 __rtnl_newlink+0xf18/0x1590 net/core/rtnetlink.c: rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3391 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5454 netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 sys_sendmsg+0x6bf/0x7e0 net/socket.c:2362 ___sys_sendmsg+0x100/0x170 net/socket.c:2416 __sys_sendmsg+0xec/0x1b0 net/socket.c:2449 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x449409 Code: e8 cc 14 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 9b 0c fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:7fa3c088fdb8 EFLAGS: 0246 ORIG_RAX: 002e RAX: ffda RBX: 006dfca8 RCX: 00449409 RDX: RSI: 2040 RDI: 000e RBP: 006dfca0 R08: 0014 R09: R10: 0001 R11: 0246 R12: 006dfcac R13: 7ffc318e2f1f R14: 7fa3c08909c0 R15: 006dfcac Kernel Offset: disabled Rebooting in 86400 seconds..
Re: WARNING: proc registration bug in snmp6_register_dev
On Thu, 16 Apr 2020 at 07:46, syzbot
wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:ab6f762f printk: queue wake_up_klogd irq_work only if per-..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1395613fe0
> kernel config: https://syzkaller.appspot.com/x/.config?x=3010ccb0f380f660
> dashboard link: https://syzkaller.appspot.com/bug?extid=1d51c8b74efa4c44adeb
> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/
> c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+1d51c8b74efa4c44a...@syzkaller.appspotmail.com
>
> [ cut here ]
> proc_dir_entry 'dev_snmp6/hsr1' already registered
> WARNING: CPU: 0 PID: 22141 at fs/proc/generic.c:363 proc_register+0x2bc/0x4e0
> fs/proc/generic.c:362
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 22141 Comm: syz-executor.2 Not tainted 5.6.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x1e9/0x30e lib/dump_stack.c:118
> panic+0x264/0x7a0 kernel/panic.c:221
> __warn+0x209/0x210 kernel/panic.c:582
> report_bug+0x1ac/0x2d0 lib/bug.c:195
> fixup_bug arch/x86/kernel/traps.c:175 [inline]
> do_error_trap+0xca/0x1c0 arch/x86/kernel/traps.c:267
> do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> RIP: 0010:proc_register+0x2bc/0x4e0 fs/proc/generic.c:362
> Code: 08 4c 8b 74 24 28 48 8b 6c 24 20 74 08 48 89 ef e8 99 29 d1 ff 48 8b 55
> 00 48 c7 c7 24 4e e9 88 48 89 de 31 c0 e8 e4 7c 65 ff <0f> 0b 48 c7 c7 20 e6
> 32 89 e8 66 41 2a 06 48 8b 44 24 30 42 8a 04
> RSP: :c900088feec0 EFLAGS: 00010246
> RAX: f20851673ab1bb00 RBX: 8880908a5264 RCX: 0004
> RDX: c9000df22000 RSI: 000150b4 RDI: 000150b5
> RBP: 88808981bc18 R08: 815cac69 R09: ed1015d06660
> R10: ed1015d06660 R11: R12: dc00
> R13: 0004 R14: 88808981bbd4 R15: 88808981bb40
> proc_create_single_data+0x18e/0x1e0 fs/proc/generic.c:631
> snmp6_register_dev+0xa1/0x110 net/ipv6/proc.c:254
> ipv6_add_dev+0x509/0x1430 net/ipv6/addrconf.c:408
> addrconf_notify+0x5f8/0x3ad0 net/ipv6/addrconf.c:3503
> notifier_call_chain kernel/notifier.c:83 [inline]
> __raw_notifier_call_chain kernel/notifier.c:361 [inline]
> raw_notifier_call_chain+0xd4/0x170 kernel/notifier.c:368
> call_netdevice_notifiers_info net/core/dev.c:1948 [inline]
> call_netdevice_notifiers_extack net/core/dev.c:1960 [inline]
> call_netdevice_notifiers net/core/dev.c:1974 [inline]
> register_netdevice+0x14a4/0x1a50 net/core/dev.c:9421
> hsr_dev_finalize+0x425/0x6d0 net/hsr/hsr_device.c:486
> hsr_newlink+0x3b5/0x460 net/hsr/hsr_netlink.c:77
> __rtnl_newlink net/core/rtnetlink.c: [inline]
> rtnl_newlink+0x143e/0x1c00 net/core/rtnetlink.c:3391
> rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5454
> netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2469
> netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
> netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1329
> netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1918
> sock_sendmsg_nosec net/socket.c:652 [inline]
> sock_sendmsg net/socket.c:672 [inline]
> sys_sendmsg+0x4f9/0x7c0 net/socket.c:2362
> ___sys_sendmsg net/socket.c:2416 [inline]
> __sys_sendmsg+0x2a6/0x360 net/socket.c:2449
> do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
> entry_SYSCALL_64_after_hwframe+0x49/0xb3
> RIP: 0033:0x45c889
> Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48
> 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f
> 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:7f007299ac78 EFLAGS: 0246 ORIG_RAX: 002e
> RAX: ffda RBX: 7f007299b6d4 RCX: 0045c889
> RDX: RSI: 20c0 RDI: 0006
> RBP: 0076c180 R08: R09:
> R10: R11: 0246 R12:
> R13: 09fc R14: 004ccb7c R15: 0076c18c
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
This is hsr module bug.
When a hsr interface is being removed,
"/proc/net/dev_snmp6/" is removed and it is created again
because of NETDEV_CHANGEMTU after NETDEV_UNREGISTER.
So, this resource can't be released in the RTNL mutex critical section.
This remained resources will be released by netdev_run_todo() but it is
not protected by RTNL mutex. So that creating a new interface
routine(rtnl_newlink()) can be executed concurrently.
This routine would try to create the same proc entry
("/proc/net/dev_snmp6/")
At
