[syzbot] [net?] WARNING: refcount bug in ethnl_phy_done

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a9b1fab3b69f Merge branch 'ionic-convert-rx-queue-buffers-..
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1193c49f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=37742f4fda0d1b09
dashboard link: https://syzkaller.appspot.com/bug?extid=e9ed4e4368d450c8f9db
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14bb7bc7980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17b0a100580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0459f959b12d/disk-a9b1fab3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/337f1be5353b/vmlinux-a9b1fab3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0e3701969c4a/bzImage-a9b1fab3.xz

The issue was bisected to:

commit 17194be4c8e1e82d8b484e58cdcb495c0714d1fd
Author: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
Date:   Wed Aug 21 15:10:01 2024 +0000

    net: ethtool: Introduce a command to list PHYs on an interface

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1034a49f980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1234a49f980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1434a49f980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e9ed4e4368d450c8f9db@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 17194be4c8e1 ("net: ethtool: Introduce a command to list PHYs on an interface")

------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 0 PID: 5227 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Modules linked in:
CPU: 0 UID: 0 PID: 5227 Comm: syz-executor281 Not tainted 6.11.0-rc6-syzkaller-01235-ga9b1fab3b69f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Code: b2 00 00 00 e8 e7 09 e1 fc 5b 5d c3 cc cc cc cc e8 db 09 e1 fc c6 05 56 d4 4f 0b 01 90 48 c7 c7 c0 3b 60 8c e8 f7 2d a3 fc 90 <0f> 0b 90 90 eb d9 e8 bb 09 e1 fc c6 05 33 d4 4f 0b 01 90 48 c7 c7
RSP: 0018:ffffc900033ff048 EFLAGS: 00010246
RAX: 033d767773c83300 RBX: ffff88802f8d0664 RCX: ffff8880506e0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000004 R08: ffffffff8155b372 R09: 1ffff1101710519a
R10: dffffc0000000000 R11: ffffed101710519b R12: ffff88802f8d0620
R13: 0000000000000000 R14: ffff88802f8d0664 R15: dffffc0000000000
FS:  00005555884f4380(0000) GS:ffff8880b8800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c9aad930a8 CR3: 0000000052acc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_dec include/linux/refcount.h:336 [inline]
 refcount_dec include/linux/refcount.h:351 [inline]
 ref_tracker_free+0x6af/0x7e0 lib/ref_tracker.c:236
 netdev_tracker_free include/linux/netdevice.h:4057 [inline]
 netdev_put include/linux/netdevice.h:4074 [inline]
 ethnl_parse_header_dev_put net/ethtool/netlink.h:271 [inline]
 ethnl_phy_done+0x6f/0x100 net/ethtool/phy.c:238
 genl_done+0x136/0x210 net/netlink/genetlink.c:1043
 netlink_dump+0x9b2/0xd80 net/netlink/af_netlink.c:2370
 __netlink_dump_start+0x5a2/0x790 net/netlink/af_netlink.c:2440
 genl_family_rcv_msg_dumpit net/netlink/genetlink.c:1076 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:1192 [inline]
 genl_rcv_msg+0x88c/0xec0 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357
 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:745
 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597
 ___sys_sendmsg net/socket.c:2651 [inline]
 __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7cf874a219
Code: 48 83 c4 28 c3 e8 e7 18 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffff97db218 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffff97db3e8 RCX: 00007f7cf874a219
RDX: 0000000000000000 RSI: 0000000020001900 RDI: 0000000000000003
RBP: 00007f7cf87bc610 R08: 00007ffff97db3e8 R09: 00007ffff97db3e8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffff97db3d8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>


---
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