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AJvYcCVjLa9AWjYeKWQu5dc3i6IT0qH6Br4IM8Pb1vbk5rwwQexQEcfBd472jDtpKw1RKrBeP6XzUWk=@vger.kernel.org X-Gm-Message-State: AOJu0Yz3HNPERBN8n2Odxtk2NCjFfVfriRywHqWffP5JnZJj4lMK7i8Q CipK+e0g/eq83bdcDBvFxo5MaKBfQwQtqPOwj104ewcbhuzN9ZRsr7qlLOF0lD7K9bzo6uBxwr1 fJTNG7ps0n+eTwtgEpwDg0DzNVoLz/yyeQ/5tll46lSs2ZTHKHfWl/FfAXzY= X-Google-Smtp-Source: AGHT+IF26XOIwoqn7XoCgF2pbJnVnnS+jDcvBdg3uxxLuPFgYOz1TlJqcCqSPMhUW3+f05h5FdkCaH6S5O5185rDhP3cbWb3cm95 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:168e:b0:3f6:69ec:ea1e with SMTP id e9e14a558f8ab-3fd963dc775mr4244575ab.23.1757104711604; Fri, 05 Sep 2025 13:38:31 -0700 (PDT) Date: Fri, 05 Sep 2025 13:38:31 -0700 In-Reply-To: <683d677f.a00a0220.d8eae.004b.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68bb4a47.a00a0220.eb3d.001a.GAE@google.com> Subject: Re: [syzbot] [net?] possible deadlock in __netdev_update_features From: syzbot To: andrew@lunn.ch, davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, stfomichev@gmail.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: d69eb204c255 Merge tag 'net-6.17-rc5' of git://git.kernel... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13a2f162580000 kernel config: https://syzkaller.appspot.com/x/.config?x=9c302bcfb26a48af dashboard link: https://syzkaller.appspot.com/bug?extid=7e0f89fb6cae5d002de0 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12942962580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16942962580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/d2a8d25d4378/disk-d69eb204.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/4574714ede3c/vmlinux-d69eb204.xz kernel image: https://storage.googleapis.com/syzbot-assets/e5bae1ec81fb/bzImage-d69eb204.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7e0f89fb6cae5d002de0@syzkaller.appspotmail.com netlink: 8 bytes leftover after parsing attributes in process `syz.0.17'. netdevsim netdevsim0 netdevsim0: entered promiscuous mode macsec1: entered allmulticast mode netdevsim netdevsim0 netdevsim0: entered allmulticast mode ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.17/6023 is trying to acquire lock: ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2761 [inline] ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_sync_lower_features net/core/dev.c:10649 [inline] ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: __netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819 but task is already holding lock: ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2761 [inline] ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: __dev_ethtool net/ethtool/ioctl.c:3235 [inline] ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: dev_ethtool+0x716/0x19b0 net/ethtool/ioctl.c:3502 and the lock comparison function returns 0: other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&dev_instance_lock_key#20); lock(&dev_instance_lock_key#20); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by syz.0.17/6023: #0: ffffffff8f539288 (rtnl_mutex){+.+.}-{4:4}, at: dev_ethtool+0x1d0/0x19b0 net/ethtool/ioctl.c:3501 #1: ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2761 [inline] #1: ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] #1: ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: __dev_ethtool net/ethtool/ioctl.c:3235 [inline] #1: ffff88802911cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: dev_ethtool+0x716/0x19b0 net/ethtool/ioctl.c:3502 stack backtrace: CPU: 1 UID: 0 PID: 6023 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 netdev_lock include/linux/netdevice.h:2761 [inline] netdev_lock_ops include/net/netdev_lock.h:42 [inline] netdev_sync_lower_features net/core/dev.c:10649 [inline] __netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819 netdev_update_features+0x6d/0xe0 net/core/dev.c:10876 macsec_notify+0x2f5/0x660 drivers/net/macsec.c:4533 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] netdev_features_change+0x85/0xc0 net/core/dev.c:1570 __dev_ethtool net/ethtool/ioctl.c:3469 [inline] dev_ethtool+0x1536/0x19b0 net/ethtool/ioctl.c:3502 dev_ioctl+0x392/0x1150 net/core/dev_ioctl.c:759 sock_do_ioctl+0x22c/0x300 net/socket.c:1252 sock_ioctl+0x576/0x790 net/socket.c:1359 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f08c1f8ebe9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff0a699878 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f08c21c5fa0 RCX: 00007f08c1f8ebe9 RDX: 0000200000000080 RSI: 0000000000008946 RDI: 0000000000000006 RBP: 00007f08c2011e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f08c21c5fa0 R14: 00007f08c21c5fa0 R15: 0000000000000003 --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.