Subject: [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info

From: syzbot <[email-masked]>
Date: Tue, 03 Aug 2021 09:07:19 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    1187c8c4642d net: phy: mscc: make some arrays static const..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=140e7b3e300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f9bb42efdc6f1d7
dashboard link: https://syzkaller.appspot.com/bug?extid=c5ac86461673ef58847c
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

FS-Cache: Netfs 'afs' registered for caching
Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes
Key type big_key registered
Key type encrypted registered
AppArmor: AppArmor sha1 policy hashing enabled
ima: No TPM chip found, activating TPM-bypass!
Loading compiled-in module X.509 certificates
Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77'
ima: Allocated hash algorithm: sha256
ima: No architecture policies found
evm: Initialising EVM extended attributes:
evm: security.selinux (disabled)
evm: security.SMACK64 (disabled)
evm: security.SMACK64EXEC (disabled)
evm: security.SMACK64TRANSMUTE (disabled)
evm: security.SMACK64MMAP (disabled)
evm: security.apparmor
evm: security.ima
evm: security.capability
evm: HMAC attrs: 0x1
PM:   Magic number: 1:990:690
printk: console [netcon0] enabled
netconsole: network logging started
gtp: GTP module loaded (pdp ctx size 104 bytes)
rdma_rxe: loaded
cfg80211: Loading compiled-in X.509 certificates for regulatory database
cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
ALSA device list:
  #0: Dummy 1
  #1: Loopback 1
  #2: Virtual MIDI Card 1
md: Waiting for all devices to be available before autodetect
md: If you don't use raid, use raid=noautodetect
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
EXT4-fs (sda1): mounted filesystem without journal. Opts: (null). Quota mode: none.
VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
devtmpfs: mounted
Freeing unused kernel image (initmem) memory: 4476K
Write protecting the kernel read-only data: 169984k
Freeing unused kernel image (text/rodata gap) memory: 2012K
Freeing unused kernel image (rodata/data gap) memory: 1516K
Run /sbin/init as init process
systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
systemd[1]: Detected virtualization kvm.
systemd[1]: Detected architecture x86-64.
systemd[1]: Set hostname to <syzkaller>.
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 1 Comm: systemd Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Code: 09 31 ff 89 de e8 d7 fa 9e fd 84 db 0f 85 36 ff ff ff e8 8a f4 9e fd 48 c7 c7 c0 81 e3 89 c6 05 70 51 81 09 01 e8 48 f8 13 05 <0f> 0b e9 17 ff ff ff e8 6b f4 9e fd 0f b6 1d 55 51 81 09 31 ff 89
RSP: 0018:ffffc90000c66ab0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88813fe48000 RSI: ffffffff815d7b25 RDI: fffff5200018cd48
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff815d195e R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000001 R14: 0000000000000000 R15: ffff888027722e00
FS:  00007f8c1c5d0500(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ed0ced4368 CR3: 0000000026bac000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 fib_create_info+0x36af/0x4910 net/ipv4/fib_semantics.c:1554
 fib_table_insert+0x1cd/0x1af0 net/ipv4/fib_trie.c:1224
 fib_magic+0x455/0x540 net/ipv4/fib_frontend.c:1087
 fib_add_ifaddr+0x16c/0x500 net/ipv4/fib_frontend.c:1109
 fib_inetaddr_event+0x162/0x2a0 net/ipv4/fib_frontend.c:1420
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 blocking_notifier_call_chain kernel/notifier.c:337 [inline]
 blocking_notifier_call_chain+0x67/0x90 kernel/notifier.c:325
 __inet_insert_ifa+0x919/0xc20 net/ipv4/devinet.c:553
 inet_insert_ifa net/ipv4/devinet.c:560 [inline]
 inetdev_event+0x1243/0x15d0 net/ipv4/devinet.c:1570
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2123
 call_netdevice_notifiers_extack net/core/dev.c:2135 [inline]
 call_netdevice_notifiers net/core/dev.c:2149 [inline]
 __dev_notify_flags+0x110/0x2b0 net/core/dev.c:8878
 dev_change_flags+0x112/0x170 net/core/dev.c:8916
 do_setlink+0x913/0x3910 net/core/rtnetlink.c:2710
 rtnl_setlink+0x24d/0x3c0 net/core/rtnetlink.c:3003
 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5563
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 __sys_sendto+0x21c/0x320 net/socket.c:2030
 __do_sys_sendto net/socket.c:2042 [inline]
 __se_sys_sendto net/socket.c:2038 [inline]
 __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2038
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f8c1ae6d693
Code: 79 20 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb cd 66 0f 1f 44 00 00 83 3d 39 bd 20 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 cb f7 ff ff 48 89 04 24
RSP: 002b:00007fffa5944aa8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055ed0ceca9a0 RCX: 00007f8c1ae6d693
RDX: 0000000000000020 RSI: 000055ed0ceca2b0 RDI: 0000000000000004
RBP: 000055ed0cecaab0 R08: 00007fffa5944ab0 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffa5944b14
R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000001

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