Subject: [syzbot] WARNING in ethnl_default_doit

From: syzbot <[email-masked]>
Date: Fri, 11 Jun 2021 15:24:26 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    1a42624a net: dsa: xrs700x: allow HSR/PRP supervision dupe..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15043cebd00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cbe37cfd20d4573c
dashboard link: https://syzkaller.appspot.com/bug?extid=59aa77b92d06cd5a54f2

Unfortunately, I don't have any reproducer for this issue yet.

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

------------[ cut here ]------------
calculated message payload length (684) not sufficient
WARNING: CPU: 0 PID: 30967 at net/ethtool/netlink.c:369 ethnl_default_doit+0x87a/0xa20 net/ethtool/netlink.c:369
Modules linked in:
CPU: 1 PID: 30967 Comm: syz-executor.0 Not tainted 5.13.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ethnl_default_doit+0x87a/0xa20 net/ethtool/netlink.c:369
Code: e8 6b b3 2b fa 40 84 ed 0f 85 f9 fd ff ff e8 ad ac 2b fa 8b 74 24 10 48 c7 c7 e0 76 6e 8a c6 05 0b ee 6b 06 01 e8 d9 df 8c 01 <0f> 0b e9 d6 fd ff ff e8 0a c0 70 fa e9 52 f8 ff ff 48 89 de 48 c7
RSP: 0018:ffffc9001731f578 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffffffff8a6e8e60 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815ce355 RDI: fffff52002e63ea1
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815c81be R11: 0000000000000000 R12: 00000000ffffffa6
R13: ffff88801d587380 R14: ffff88802d919800 R15: 1ffff92002e63eb4
FS:  00007fb7d20ef700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2cb23000 CR3: 00000000548f7000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739
 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb7d20ef188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000020000000 RSI: 0000000020000400 RDI: 0000000000000004
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffd1ef3866f R14: 00007fb7d20ef300 R15: 0000000000022000

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