Re: WARNING in dev_change_net_namespace

[Eric W. Biederman]

syzbot <syzbot+830c6dbfc71edc4f0b8f@xxxxxxxxxxxxxxxxxxxxxxxxx> writes:

> Hello,

Has someone messed up the network device kobject support.
I don't have the exact same code as listed here so I may
be misreading things.  But the only WARN_ON I see in
dev_change_net_namespaces is from kobject_rename.

It is not supposed to be possible for that to fail.

Historically it only failed when network devices were put into sysfs
in a way that required network devices to have names separate from
sysfs files.  We fixed that ages ago, so I don't have a clue why
kobject_rename would be failing now.

szybot any idea what network device was changing network namespaces?

Eric


> syzbot found the following crash on:
>
> HEAD commit:    0a679e13 Merge branch 'for-5.6-fixes' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15142701e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=6780df5a5f208964
> dashboard link: https://syzkaller.appspot.com/bug?extid=830c6dbfc71edc4f0b8f
> 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+830c6dbfc71edc4f0b8f@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000004
> RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
> R13: 00000000000009cb R14: 00000000004cb3dd R15: 0000000000000016
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 24839 at net/core/dev.c:10108 dev_change_net_namespace+0x155f/0x16b0 net/core/dev.c:10108
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 24839 Comm: syz-executor.4 Not tainted 5.6.0-rc1-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+0x1fb/0x318 lib/dump_stack.c:118
>  panic+0x264/0x7a9 kernel/panic.c:221
>  __warn+0x209/0x210 kernel/panic.c:582
>  report_bug+0x1b6/0x2f0 lib/bug.c:195
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  do_error_trap+0xcf/0x1c0 arch/x86/kernel/traps.c:267
>  do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:286
>  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> RIP: 0010:dev_change_net_namespace+0x155f/0x16b0 net/core/dev.c:10108
> Code: b7 f9 02 01 48 c7 c7 5d 66 e6 88 48 c7 c6 b4 42 04 89 ba 25 27 00 00 31 c0 e8 6d a6 dc fa 0f 0b e9 0d eb ff ff e8 a1 e6 0a fb <0f> 0b e9 2f fe ff ff e8 95 e6 0a fb c6 05 05 b7 f9 02 01 48 c7 c7
> RSP: 0018:ffffc90001ae7140 EFLAGS: 00010246
> RAX: ffffffff866c18df RBX: 00000000fffffff4 RCX: 0000000000040000
> RDX: ffffc90012028000 RSI: 000000000003ffff RDI: 0000000000040000
> RBP: ffffc90001ae7240 R08: ffffffff866c1700 R09: fffffbfff1406318
> R10: fffffbfff1406318 R11: 0000000000000000 R12: ffff8880918d2b60
> R13: ffff8880918d20b8 R14: ffffc90001ae71e8 R15: ffffc90001ae71e0
>  do_setlink+0x196/0x3880 net/core/rtnetlink.c:2501
>  __rtnl_newlink net/core/rtnetlink.c:3252 [inline]
>  rtnl_newlink+0x1509/0x1c00 net/core/rtnetlink.c:3377
>  rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5438
>  netlink_rcv_skb+0x19e/0x3e0 net/netlink/af_netlink.c:2477
>  rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5456
>  netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
>  netlink_unicast+0x766/0x920 net/netlink/af_netlink.c:1328
>  netlink_sendmsg+0xa2b/0xd40 net/netlink/af_netlink.c:1917
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg net/socket.c:672 [inline]
>  ____sys_sendmsg+0x4f7/0x7f0 net/socket.c:2343
>  ___sys_sendmsg net/socket.c:2397 [inline]
>  __sys_sendmsg+0x1ed/0x290 net/socket.c:2430
>  __do_sys_sendmsg net/socket.c:2439 [inline]
>  __se_sys_sendmsg net/socket.c:2437 [inline]
>  __x64_sys_sendmsg+0x7f/0x90 net/socket.c:2437
>  do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x45b3b9
> 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:00007f483611ac78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f483611b6d4 RCX: 000000000045b3b9
> RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000004
> RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
> R13: 00000000000009cb R14: 00000000004cb3dd R15: 0000000000000016
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
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