From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f78.google.com (mail-oo1-f78.google.com [209.85.161.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 605A933D6EA for ; Tue, 19 May 2026 18:53:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779216820; cv=none; b=ExTXEhDrD9i5N8fcSMDGFEZowtsIiTGjg7Vn0RJZK59dQUTbxx+liy0s0E8HFQlkXHp4Brv9Dn5NN1yEBxHJH3fZ2Dlp+ms2EPmBfziA8XJUhhoBJE9NvPJ/DrcLg3tAQwRaJu+Yu0oHH5amED+Ow6jDU9Z8llNrD9g6mogBsJ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779216820; c=relaxed/simple; bh=d1TFxgswi4mJWm/z3zIfG6YsxfWxlN3KnG0dAtdeERs=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=CoLxQqPzqKXyFlk/BsCbyQ3HzLn8rBO56VWXwNFVhOLt9UCKBoS9eEaS5y5H4VWWHTVCXpGQy+jYi+BhiWx87pTb/seAkj9mrS5b0R19hTRDueq25FPM/SPVBsgz1sPBWBp486fPMg7zmY8cbhyj3zn1GCfhvNFPP8mOrHIr0cI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.161.78 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo1-f78.google.com with SMTP id 006d021491bc7-69b91d4f9b1so9578688eaf.3 for ; Tue, 19 May 2026 11:53:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779216817; x=1779821617; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=WiEvteoaqOMoFc3FA5qwqDWyPrKiPeyEd1Uk75GF9D4=; b=jukFXODM5I83sG+UmmO/j/BMtpiqce7auUXybI9kK2bq5gvzMxeyWN9CBC7B2d/fou KmdnRikJCk23K4B7MQWm9Vzaql+n2MTLeG0dXEUSh+L8DI3XqXiMEQy2w3Dx63I3Xpcl jzuMSmLoBI5BFMH+IBrvhKrEHdKkULLJx/YdZDZi7D2tANzt24oqS3KPsdhP/FkcROET yEDLKF89xcXn9wC0ZYDpxdiqZRw+GLcVB4UQiPx6TKp4qh3OnEt4s2jdp4301DGqxtrq btXxxa7aYCFTflrWtCjLfLdfs41AfJbGWpdUuXZ8QnUOk2yCN95TY/3pf/pHZzYccBT1 j1lg== X-Forwarded-Encrypted: i=1; AFNElJ9sFNp0QtmbUYSXA23Kw0FHnVVX7iHDy77SHi/CphasO/8dku6MRyLUc0Yk1kgYNsNH492zaOY=@vger.kernel.org X-Gm-Message-State: AOJu0YwcvPFMUWtBqzAglD60zOAbO5OaNvLpSU/fHjbadpXulCbE5q92 vryIQeSIGNsnxaOVNS2urQgc+ZabGnEhrbDQ9HrQHdiXTUEpmQLcfNIEELbzyi2lAFiLN0joKIt F2o2x+MyOck8o8JR9JRs7lKSDmLMOPJrcozX0pRVptLC+fnA5F80RHejopz0= Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1f06:b0:694:8f3a:3f3d with SMTP id 006d021491bc7-69c94375246mr13243096eaf.35.1779216817247; Tue, 19 May 2026 11:53:37 -0700 (PDT) Date: Tue, 19 May 2026 11:53:37 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a0cb1b1.170a0220.1f6c2d.0001.GAE@google.com> Subject: [syzbot] [net?] possible deadlock in __sk_receive_skb From: syzbot To: courmisch@gmail.com, davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 97e797263a5e Add linux-next specific files for 20260420 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=17c62c36580000 kernel config: https://syzkaller.appspot.com/x/.config?x=354b135d724a721f dashboard link: https://syzkaller.appspot.com/bug?extid=9f4a135646b66c509935 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10f622d2580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f88e6a580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/bfe08255b02b/disk-97e79726.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/70874e341331/vmlinux-97e79726.xz kernel image: https://storage.googleapis.com/syzbot-assets/68352f7fca94/bzImage-97e79726.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9f4a135646b66c509935@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.17/6130 is trying to acquire lock: ffff88803976da20 (slock-AF_PHONET/1){+.+.}-{3:3}, at: __sk_receive_skb+0x1bf/0x9e0 net/core/sock.c:563 but task is already holding lock: ffff88803976e2e0 (slock-AF_PHONET){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff88803976e2e0 (slock-AF_PHONET){+...}-{3:3}, at: __sk_receive_skb+0x1f1/0x9e0 net/core/sock.c:565 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (slock-AF_PHONET){+...}-{3:3}: rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] __sk_receive_skb+0x1f1/0x9e0 net/core/sock.c:565 sk_receive_skb include/net/sock.h:2022 [inline] phonet_rcv+0x781/0xc40 net/phonet/af_phonet.c:-1 __netif_receive_skb_one_core net/core/dev.c:6210 [inline] __netif_receive_skb net/core/dev.c:6323 [inline] process_backlog+0x5e1/0xc60 net/core/dev.c:6674 __napi_poll+0xab/0x550 net/core/dev.c:7738 napi_poll net/core/dev.c:7801 [inline] net_rx_action+0x696/0xe00 net/core/dev.c:7958 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] netif_rx+0xb9/0xf0 net/core/dev.c:5776 pn_send+0x62a/0x8e0 net/phonet/af_phonet.c:188 pn_skb_send+0x218/0x530 net/phonet/af_phonet.c:275 pep_indicate net/phonet/pep.c:123 [inline] pipe_snd_status+0x1f1/0x320 net/phonet/pep.c:221 pipe_grant_credits net/phonet/pep.c:244 [inline] pipe_do_rcv+0xf15/0x16a0 net/phonet/pep.c:433 sk_backlog_rcv include/net/sock.h:1190 [inline] __sk_receive_skb+0x962/0x9e0 net/core/sock.c:572 sk_receive_skb include/net/sock.h:2022 [inline] pep_do_rcv+0x685/0xaa0 net/phonet/pep.c:675 sk_backlog_rcv include/net/sock.h:1190 [inline] __release_sock+0x2a9/0x3d0 net/core/sock.c:3216 release_sock+0x1be/0x290 net/core/sock.c:3815 pep_sock_accept+0xd47/0x11e0 net/phonet/pep.c:879 pn_socket_accept+0xc1/0x310 net/phonet/socket.c:303 do_accept+0x6ca/0x930 net/socket.c:2062 __sys_accept4_file net/socket.c:2096 [inline] __sys_accept4+0x139/0x230 net/socket.c:2118 __do_sys_accept4 net/socket.c:2125 [inline] __se_sys_accept4 net/socket.c:2122 [inline] __x64_sys_accept4+0x9a/0xb0 net/socket.c:2122 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (slock-AF_PHONET/1){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3167 [inline] check_prevs_add kernel/locking/lockdep.c:3286 [inline] validate_chain kernel/locking/lockdep.c:3910 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5239 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870 rt_spin_lock_nested+0x81/0x3f0 kernel/locking/spinlock_rt.c:64 __sk_receive_skb+0x1bf/0x9e0 net/core/sock.c:563 sk_receive_skb include/net/sock.h:2022 [inline] pep_do_rcv+0x685/0xaa0 net/phonet/pep.c:675 sk_backlog_rcv include/net/sock.h:1190 [inline] __sk_receive_skb+0x962/0x9e0 net/core/sock.c:572 sk_receive_skb include/net/sock.h:2022 [inline] phonet_rcv+0x781/0xc40 net/phonet/af_phonet.c:-1 __netif_receive_skb_one_core net/core/dev.c:6210 [inline] __netif_receive_skb net/core/dev.c:6323 [inline] process_backlog+0x5e1/0xc60 net/core/dev.c:6674 __napi_poll+0xab/0x550 net/core/dev.c:7738 napi_poll net/core/dev.c:7801 [inline] net_rx_action+0x696/0xe00 net/core/dev.c:7958 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] netif_rx+0xb9/0xf0 net/core/dev.c:5776 pn_send+0x62a/0x8e0 net/phonet/af_phonet.c:188 pn_skb_send+0x218/0x530 net/phonet/af_phonet.c:275 pipe_skb_send+0x2f7/0x540 net/phonet/pep.c:1130 pep_sendmsg+0x9ca/0xb00 net/phonet/pep.c:1206 pn_socket_sendmsg+0x1e5/0x250 net/phonet/socket.c:424 sock_sendmsg_nosec+0x112/0x150 net/socket.c:797 __sock_sendmsg net/socket.c:812 [inline] sock_write_iter+0x308/0x410 net/socket.c:1269 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x629/0xba0 fs/read_write.c:688 ksys_write+0x156/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slock-AF_PHONET); lock(slock-AF_PHONET/1); lock(slock-AF_PHONET); lock(slock-AF_PHONET/1); *** DEADLOCK *** 6 locks held by syz.0.17/6130: #0: ffff88803aded218 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline] #0: ffff88803aded218 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: pep_sendmsg+0x7b6/0xb00 net/phonet/pep.c:1199 #1: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #2: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #2: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: process_backlog+0x271/0xc60 net/core/dev.c:6673 #3: ffff88803976e2e0 (slock-AF_PHONET){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #3: ffff88803976e2e0 (slock-AF_PHONET){+...}-{3:3}, at: __sk_receive_skb+0x1f1/0x9e0 net/core/sock.c:565 #4: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #4: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #4: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #4: ffffffff8e3c8140 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #5: ffff88803976e398 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: sk_receive_skb include/net/sock.h:2022 [inline] #5: ffff88803976e398 (sk_lock-AF_PHONET){+.+.}-{0:0}, at: phonet_rcv+0x781/0xc40 net/phonet/af_phonet.c:-1 stack backtrace: CPU: 0 UID: 0 PID: 6130 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2045 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2177 check_prev_add kernel/locking/lockdep.c:3167 [inline] check_prevs_add kernel/locking/lockdep.c:3286 [inline] validate_chain kernel/locking/lockdep.c:3910 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5239 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870 rt_spin_lock_nested+0x81/0x3f0 kernel/locking/spinlock_rt.c:64 __sk_receive_skb+0x1bf/0x9e0 net/core/sock.c:563 sk_receive_skb include/net/sock.h:2022 [inline] pep_do_rcv+0x685/0xaa0 net/phonet/pep.c:675 sk_backlog_rcv include/net/sock.h:1190 [inline] __sk_receive_skb+0x962/0x9e0 net/core/sock.c:572 sk_receive_skb include/net/sock.h:2022 [inline] phonet_rcv+0x781/0xc40 net/phonet/af_phonet.c:-1 __netif_receive_skb_one_core net/core/dev.c:6210 [inline] __netif_receive_skb net/core/dev.c:6323 [inline] process_backlog+0x5e1/0xc60 net/core/dev.c:6674 __napi_poll+0xab/0x550 net/core/dev.c:7738 napi_poll net/core/dev.c:7801 [inline] net_rx_action+0x696/0xe00 net/core/dev.c:7958 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] netif_rx+0xb9/0xf0 net/core/dev.c:5776 pn_send+0x62a/0x8e0 net/phonet/af_phonet.c:188 pn_skb_send+0x218/0x530 net/phonet/af_phonet.c:275 pipe_skb_send+0x2f7/0x540 net/phonet/pep.c:1130 pep_sendmsg+0x9ca/0xb00 net/phonet/pep.c:1206 pn_socket_sendmsg+0x1e5/0x250 net/phonet/socket.c:424 sock_sendmsg_nosec+0x112/0x150 net/socket.c:797 __sock_sendmsg net/socket.c:812 [inline] sock_write_iter+0x308/0x410 net/socket.c:1269 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x629/0xba0 fs/read_write.c:688 ksys_write+0x156/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd74410c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd743745028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fd744386090 RCX: 00007fd74410c819 RDX: 00000000000003db RSI: 0000200000000480 RDI: 0000000000000006 RBP: 00007fd7441a2c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd744386128 R14: 00007fd744386090 R15: 00007fff7efc5418 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup