[syzbot] [net?] WARNING: suspicious RCU usage in inetdev_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    144e22e7569a selftests/net: Add log.txt and tools to .giti..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1706640fa80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=aa796b6080b04102
dashboard link: https://syzkaller.appspot.com/bug?extid=c670c371a962d1334881
compiler:       gcc (Debian 12.2.0-14) 12.2.0, 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/c2b82060a69a/disk-144e22e7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b660bbc0308/vmlinux-144e22e7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/243ca7530ae8/bzImage-144e22e7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c670c371a962d1334881@xxxxxxxxxxxxxxxxxxxxxxxxx

=============================
WARNING: suspicious RCU usage
6.5.0-rc6-syzkaller-00144-g144e22e7569a #0 Not tainted
-----------------------------
include/linux/inetdevice.h:250 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor.4/21034:
 #0: ffffffff8e47afb0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1077
 #1: ffffffff8e47b068 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
 #1: ffffffff8e47b068 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x573/0x800 net/netlink/genetlink.c:1065

stack backtrace:
CPU: 0 PID: 21034 Comm: syz-executor.4 Not tainted 6.5.0-rc6-syzkaller-00144-g144e22e7569a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x125/0x1b0 lib/dump_stack.c:106
 lockdep_rcu_suspicious+0x20c/0x3b0 kernel/locking/lockdep.c:6719
 __in_dev_get_rtnl include/linux/inetdevice.h:250 [inline]
 inetdev_event+0x444/0x1900 net/ipv4/devinet.c:1532
 notifier_call_chain+0xb6/0x3b0 kernel/notifier.c:93
 call_netdevice_notifiers_info+0xb9/0x130 net/core/dev.c:1962
 call_netdevice_notifiers_extack net/core/dev.c:2000 [inline]
 call_netdevice_notifiers net/core/dev.c:2014 [inline]
 dev_set_mtu_ext+0x1e8/0x5d0 net/core/dev.c:8664
 dev_set_mtu+0xb1/0x160 net/core/dev.c:8694
 batadv_update_min_mtu+0x6e/0x90 net/batman-adv/hard-interface.c:645
 batadv_netlink_set_mesh+0x7d8/0x14e0 net/batman-adv/netlink.c:498
 genl_family_rcv_msg_doit.isra.0+0x1ef/0x2d0 net/netlink/genetlink.c:970
 genl_family_rcv_msg net/netlink/genetlink.c:1050 [inline]
 genl_rcv_msg+0x559/0x800 net/netlink/genetlink.c:1067
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2549
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1078
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x539/0x800 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x93c/0xe30 net/netlink/af_netlink.c:1914
 sock_sendmsg_nosec net/socket.c:725 [inline]
 sock_sendmsg+0xd9/0x180 net/socket.c:748
 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2494
 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2548
 __sys_sendmsg+0x117/0x1e0 net/socket.c:2577
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0093a7cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f00948330c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f0093b9bf80 RCX: 00007f0093a7cae9
RDX: 0000000000000000 RSI: 00000000200005c0 RDI: 0000000000000003
RBP: 00007f0093ac847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0093b9bf80 R15: 00007ffdab8adf58
 </TASK>
------------[ cut here ]------------
RTNL: assertion failed at net/ipv4/devinet.c (1534)
WARNING: CPU: 1 PID: 21034 at net/ipv4/devinet.c:1534 inetdev_event+0x1142/0x1900 net/ipv4/devinet.c:1534
Modules linked in:
CPU: 1 PID: 21034 Comm: syz-executor.4 Not tainted 6.5.0-rc6-syzkaller-00144-g144e22e7569a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:inetdev_event+0x1142/0x1900 net/ipv4/devinet.c:1534
Code: 0f 85 d1 ef ff ff e8 2d 8c c7 f8 ba fe 05 00 00 48 c7 c6 60 62 8d 8b 48 c7 c7 a0 62 8d 8b c6 05 03 5a d7 05 01 e8 4e 4e 8e f8 <0f> 0b e9 a6 ef ff ff e8 02 8c c7 f8 4c 89 ef e8 da cb ff ff 48 c7
RSP: 0018:ffffc900068b7190 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000018 RCX: ffffc90014f77000
RDX: 0000000000040000 RSI: ffffffff814ccc86 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88802d8fc340
R13: ffff88802d8fc000 R14: ffffffff8e550860 R15: 0000000000000000
FS:  00007f00948336c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f964000 CR3: 0000000029d00000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 notifier_call_chain+0xb6/0x3b0 kernel/notifier.c:93
 call_netdevice_notifiers_info+0xb9/0x130 net/core/dev.c:1962
 call_netdevice_notifiers_extack net/core/dev.c:2000 [inline]
 call_netdevice_notifiers net/core/dev.c:2014 [inline]
 dev_set_mtu_ext+0x1e8/0x5d0 net/core/dev.c:8664
 dev_set_mtu+0xb1/0x160 net/core/dev.c:8694
 batadv_update_min_mtu+0x6e/0x90 net/batman-adv/hard-interface.c:645
 batadv_netlink_set_mesh+0x7d8/0x14e0 net/batman-adv/netlink.c:498
 genl_family_rcv_msg_doit.isra.0+0x1ef/0x2d0 net/netlink/genetlink.c:970
 genl_family_rcv_msg net/netlink/genetlink.c:1050 [inline]
 genl_rcv_msg+0x559/0x800 net/netlink/genetlink.c:1067
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2549
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1078
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x539/0x800 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x93c/0xe30 net/netlink/af_netlink.c:1914
 sock_sendmsg_nosec net/socket.c:725 [inline]
 sock_sendmsg+0xd9/0x180 net/socket.c:748
 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2494
 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2548
 __sys_sendmsg+0x117/0x1e0 net/socket.c:2577
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0093a7cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f00948330c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f0093b9bf80 RCX: 00007f0093a7cae9
RDX: 0000000000000000 RSI: 00000000200005c0 RDI: 0000000000000003
RBP: 00007f0093ac847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0093b9bf80 R15: 00007ffdab8adf58
 </TASK>


---
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