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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bc6a5efe3dcd Merge branch 'net-timestamp-selectable'
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1309c7e8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=87a291e9e8ffbb16
dashboard link: https://syzkaller.appspot.com/bug?extid=a344326c05c98ba19682
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=179802df980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=125b34f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0e3bb05cbd15/disk-bc6a5efe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/68f124e1efd7/vmlinux-bc6a5efe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c3e210387375/bzImage-bc6a5efe.xz

The issue was bisected to:

commit b9e3f7dc9ed95daeb83cfa45b821cacaa01aa906
Author: Kory Maincent <kory.m...@bootlin.com>
Date: Thu Dec 12 17:06:44 2024 +0000

net: ethtool: tsinfo: Enhance tsinfo to support several hwtstamp by net topology

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12885730580000
final oops: https://syzkaller.appspot.com/x/report.txt?x=11885730580000
console output: https://syzkaller.appspot.com/x/log.txt?x=16885730580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a34432...@syzkaller.appspotmail.com
Fixes: b9e3f7dc9ed9 ("net: ethtool: tsinfo: Enhance tsinfo to support several hwtstamp by net topology")

=============================
WARNING: suspicious RCU usage
6.13.0-rc2-syzkaller-00424-gbc6a5efe3dcd #0 Not tainted
-----------------------------
net/ethtool/common.c:873 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor164/5836:
#0: ffff888035ec8258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1617 [inline]
#0: ffff888035ec8258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1126 [inline]
#0: ffff888035ec8258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: sk_setsockopt+0xf0f/0x33b0 net/core/sock.c:1285

stack backtrace:
CPU: 0 UID: 0 PID: 5836 Comm: syz-executor164 Not tainted 6.13.0-rc2-syzkaller-00424-gbc6a5efe3dcd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6845
__ethtool_get_ts_info+0x97/0x410 net/ethtool/common.c:873
ethtool_get_phc_vclocks+0xa1/0x160 net/ethtool/common.c:922
sock_timestamping_bind_phc net/core/sock.c:873 [inline]
sock_set_timestamping+0x3e2/0xab0 net/core/sock.c:927
sk_setsockopt+0x2150/0x33b0 net/core/sock.c:1418
do_sock_setsockopt+0x2fb/0x720 net/socket.c:2309
__sys_setsockopt net/socket.c:2338 [inline]
__do_sys_setsockopt net/socket.c:2344 [inline]
__se_sys_setsockopt net/socket.c:2341 [inline]
__x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2341
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: 0033:0x7f7dd7b8f2e9
Code: 48 83 c4 28 c3 e8 37 17 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:00007ffc67b485b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007ffc67b48788 RCX: 00007f7dd7b8f2e9
RDX: 0000000000000025 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 00007f7dd7c02610 R08: 0000000000000004 R09: 00007ffc67b48788
R10: 0000000020000040 R11: 0000000000000246 R12: 0000000000000001


---
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