Subject: Re: WARNING in kernfs_add_one

From: Greg KH <[email-masked]>
Date: Sat, 5 May 2018 15:07:21 -0700

On Sat, May 05, 2018 at 10:43:45AM -0700, Eric Dumazet wrote:
> 
> 
> On 05/05/2018 09:40 AM, Greg KH wrote:
> > On Sat, May 05, 2018 at 08:47:02AM -0700, syzbot wrote:
> >> Hello,
> >>
> >> syzbot found the following crash on:
> >>
> >> HEAD commit:    8fb11a9a8d51 net/ipv6: rename rt6_next to fib6_next
> >> git tree:       net-next
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=14b27237800000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=c416c61f3cd96be
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=df47f81c226b31d89fb1
> >> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> >> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=172fb3e7800000
> >> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16552e57800000
> >>
> >> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >> Reported-by: [email-masked]
> >>
> >> RBP: 00007fff808f3e10 R08: 0000000000000002 R09: 00007fff80003534
> >> R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
> >> R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
> >> ------------[ cut here ]------------
> >> kernfs: ns required in 'ieee80211' for 'phy3'
> > 
> > That's interesting, this looks like a netfilter bug (adding netdev to
> > the report here.)
> 
> 
> I do not see anything netfilter related here.
> 
> More likely wireless territory

Ugh, that's what I get for writing emails before coffee in the
morning...

Yes, you are right, this looks like a wireless issue.

Now cc: linux-wireless.

> > Yes, we can "tone down" the kernfs warning to just be an error message
> > in the log, but there might be something worse going on here.
> > 
> > Network developers, any idea?  Rest of the callback chain is here:
> > 
> > 
> >> WARNING: CPU: 0 PID: 4538 at fs/kernfs/dir.c:759 kernfs_add_one+0x406/0x4d0
> >> fs/kernfs/dir.c:758
> >> Kernel panic - not syncing: panic_on_warn set ...
> >>
> >> CPU: 0 PID: 4538 Comm: syz-executor486 Not tainted 4.17.0-rc3+ #33
> >> 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+0x1b9/0x294 lib/dump_stack.c:113
> >>  panic+0x22f/0x4de kernel/panic.c:184
> >>  __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
> >>  report_bug+0x252/0x2d0 lib/bug.c:186
> >>  fixup_bug arch/x86/kernel/traps.c:178 [inline]
> >>  do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
> >>  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
> >>  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
> >> RIP: 0010:kernfs_add_one+0x406/0x4d0 fs/kernfs/dir.c:758
> >> RSP: 0018:ffff8801ca9eece0 EFLAGS: 00010286
> >> RAX: 000000000000002d RBX: ffffffff87d5cee0 RCX: ffffffff8160ba7d
> >> RDX: 0000000000000000 RSI: ffffffff81610731 RDI: ffff8801ca9ee840
> >> RBP: ffff8801ca9eed20 R08: ffff8801d9538500 R09: 0000000000000006
> >> R10: ffff8801d9538500 R11: 0000000000000000 R12: ffff8801ad1cb6c0
> >> R13: ffffffff885da640 R14: 0000000000000020 R15: 0000000000000000
> >>  kernfs_create_link+0x112/0x180 fs/kernfs/symlink.c:41
> >>  sysfs_do_create_link_sd.isra.2+0x90/0x130 fs/sysfs/symlink.c:43
> >>  sysfs_do_create_link fs/sysfs/symlink.c:79 [inline]
> >>  sysfs_create_link+0x65/0xc0 fs/sysfs/symlink.c:91
> >>  device_add_class_symlinks drivers/base/core.c:1612 [inline]
> >>  device_add+0x7a0/0x16d0 drivers/base/core.c:1810
> >>  wiphy_register+0x178a/0x2430 net/wireless/core.c:806
> >>  ieee80211_register_hw+0x13cd/0x35d0 net/mac80211/main.c:1047
> >>  mac80211_hwsim_new_radio+0x1d9b/0x3410
> >> drivers/net/wireless/mac80211_hwsim.c:2772
> >>  hwsim_new_radio_nl+0x7a7/0xa60 drivers/net/wireless/mac80211_hwsim.c:3246
> >>  genl_family_rcv_msg+0x889/0x1120 net/netlink/genetlink.c:599
> >>  genl_rcv_msg+0xc6/0x170 net/netlink/genetlink.c:624
> >>  netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2448
> >>  genl_rcv+0x28/0x40 net/netlink/genetlink.c:635
> >>  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> >>  netlink_unicast+0x58b/0x740 net/netlink/af_netlink.c:1336
> >>  netlink_sendmsg+0x9f0/0xfa0 net/netlink/af_netlink.c:1901
> >>  sock_sendmsg_nosec net/socket.c:629 [inline]
> >>  sock_sendmsg+0xd5/0x120 net/socket.c:639
> >>  ___sys_sendmsg+0x805/0x940 net/socket.c:2117
> >>  __sys_sendmsg+0x115/0x270 net/socket.c:2155
> >>  __do_sys_sendmsg net/socket.c:2164 [inline]
> >>  __se_sys_sendmsg net/socket.c:2162 [inline]
> >>  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2162
> >>  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
> >>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >> RIP: 0033:0x4404c9
> >> RSP: 002b:00007fff808f3e08 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> >> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004404c9
> >> RDX: 0000000000000000 RSI: 0000000020b3dfc8 RDI: 0000000000000005
> >> RBP: 00007fff808f3e10 R08: 0000000000000002 R09: 00007fff80003534
> >> R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
> >> R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
> >> Dumping ftrace buffer:
> >>    (ftrace buffer empty)
> >> Kernel Offset: disabled
> >> Rebooting in 86400 seconds..
> > 
> > 

Any ideas?

thanks,

greg k-h