From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f77.google.com (mail-ot1-f77.google.com [209.85.210.77]) (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 05B243EFD2C for ; Thu, 23 Apr 2026 13:23:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.77 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776950615; cv=none; b=rmsec+m9hlJvmQIx1ndup97CrrCdfbCBLgVO4vAIQbSluaSu38HMhmX077agvHoXy15EebKKi5LUVZrWh5zD5tD8FCTV9+PXGKpAYgUrJvsE/JB4Bb7yofu04OyvJv4VaQMlThMSNgrPRrI8N/QTCGS79ubfYPM60dJKqpUE18s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776950615; c=relaxed/simple; bh=kxR5kZe+RhUT1YsIZ7iRg17j5v51ZEPQ/oI9VX4dRiw=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=NccprhFQ50/oVy60JYkO3ajSRMSd/zgqbXtkN0ZCW31llZ71kXjsu5FMZBNX3zrjaluRHVGnWlUbrrR+0aATmitlcxLiq0lHGZwgivjd1sFM1Noe+U6w39TPl3y2UctuPpsZi+p8aq/2Qdr+4GXMJAbitkr/Xf/7rBcZMx7fM1c= 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=209.85.210.77 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-ot1-f77.google.com with SMTP id 46e09a7af769-7dcdcacd141so3852204a34.2 for ; Thu, 23 Apr 2026 06:23:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776950613; x=1777555413; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=VZIEEV94aBlR3Ds7V+JNZozyuyfwHjuccKFw4gC7tm8=; b=Nqf6bTQGh1gsEIrxUcYocktk86x+G0xJe/9vU0yCbyfaXaXYujjSWx4TrEun7sC182 1BuW4R839RoDUGSDCiSHaM+skcglX18n/eZft9YeqIjoyd5by1Bnw5QL1PA8p5fTayBf OaC7hUXW1tqjTQjISpBhgVXt9Jx2nv6+LuvLiDdzaEl7n5y5fNow7nChIeadj5NlGIZg pJPnCKrhX9YeidowratTe1cOK7R99t1XYcXDEJfavrRlR26DFZr/dkETPlTzSD4HgmPg Xly/1MCIu4srP05Wkn3WoYULmwzYbPgxzly0+ZRtT6p/Zd0qn7y9g2qpu95ChfAyDwGU qAWA== X-Forwarded-Encrypted: i=1; AFNElJ+JHxUvtBtY8G2CJ3KQy/ahU8ejJCK+oc3QUiVW3g6hjz4RSlamUp3BYlnUgyolwjpxNZ3mnVz6gzmipGA=@vger.kernel.org X-Gm-Message-State: AOJu0Yx3O3hZJC0SfScIndFAKXiU7t6fX+76BJKrtxLGtbp/VSlVCuxr YXpTjf69qmpNrdSVLhfljBNEbUevvuLPSYgR2fde/sx6p/cU4T+7IckzUJJ+XTkjLWo89puqjFV Jn5mC5e+588w+/uVIRIe9Zj2ipUrl6pfzwVZABZOnuxEEdtiIzeVh7epVq1U= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:62a:b0:67e:2e4d:6c75 with SMTP id 006d021491bc7-69462f084a4mr15429094eaf.41.1776950612826; Thu, 23 Apr 2026 06:23:32 -0700 (PDT) Date: Thu, 23 Apr 2026 06:23:32 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69ea1d54.a00a0220.9259.0027.GAE@google.com> Subject: [syzbot] [net?] WARNING: refcount bug in sk_common_release (2) From: syzbot To: davem@davemloft.net, dsahern@kernel.org, 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: 2a4c0c11c019 Merge tag 's390-7.1-1' of git://git.kernel.or.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=142dff16580000 kernel config: https://syzkaller.appspot.com/x/.config?x=3e19fa1907a3dfda dashboard link: https://syzkaller.appspot.com/bug?extid=8c9eede336e3a843750e compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-2a4c0c11.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2702dddfd186/vmlinux-2a4c0c11.xz kernel image: https://storage.googleapis.com/syzbot-assets/51878be8732c/bzImage-2a4c0c11.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8c9eede336e3a843750e@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28, CPU#1: syz.8.4131/20639 Modules linked in: CPU: 1 UID: 0 PID: 20639 Comm: syz.8.4131 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28 Code: cc e8 60 a7 0f fd 48 8d 3d 99 d0 ec 0b 67 48 0f b9 3a e8 4f a7 0f fd 5b 5d e9 48 27 a4 06 e8 43 a7 0f fd 48 8d 3d 8c d0 ec 0b <67> 48 0f b9 3a e8 32 a7 0f fd 5b 5d c3 cc cc cc cc e8 26 a7 0f fd RSP: 0018:ffffc90003aaf120 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff8880368a2280 RCX: ffffffff84f9d30b RDX: ffff888061e04a00 RSI: ffffffff84f9d39d RDI: ffffffff90e6a430 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000004 R10: 0000000000000003 R11: 0000000000000000 R12: ffff8880368a2280 R13: ffffffff8a0c6f20 R14: 0000000000000000 R15: 0000000000000018 FS: 00007fd377c686c0(0000) GS:ffff8880d63db000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b33023ffc CR3: 00000000308a1000 CR4: 0000000000352ef0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] sock_put include/net/sock.h:2009 [inline] sk_common_release+0x260/0x370 net/core/sock.c:4024 inet_release+0xed/0x200 net/ipv4/af_inet.c:442 __sock_release net/socket.c:722 [inline] sock_release+0x91/0x1c0 net/socket.c:750 rxe_release_udp_tunnel drivers/infiniband/sw/rxe/rxe_net.c:294 [inline] rxe_sock_put+0xae/0x130 drivers/infiniband/sw/rxe/rxe_net.c:639 rxe_net_del+0x83/0x120 drivers/infiniband/sw/rxe/rxe_net.c:660 rxe_dellink+0x15/0x20 drivers/infiniband/sw/rxe/rxe.c:254 nldev_dellink+0x289/0x3c0 drivers/infiniband/core/nldev.c:1849 rdma_nl_rcv_msg+0x392/0x6f0 drivers/infiniband/core/netlink.c:195 rdma_nl_rcv_skb.constprop.0.isra.0+0x2cb/0x410 drivers/infiniband/core/netlink.c:239 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752 __sys_sendmsg+0x170/0x220 net/socket.c:2784 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd376d9c819 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:00007fd377c68028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fd377016090 RCX: 00007fd376d9c819 RDX: 0000000000000004 RSI: 0000200000004680 RDI: 0000000000000003 RBP: 00007fd376e32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd377016128 R14: 00007fd377016090 R15: 00007ffe66f5e6c8 ---------------- Code disassembly (best guess): 0: cc int3 1: e8 60 a7 0f fd call 0xfd0fa766 6: 48 8d 3d 99 d0 ec 0b lea 0xbecd099(%rip),%rdi # 0xbecd0a6 d: 67 48 0f b9 3a ud1 (%edx),%rdi 12: e8 4f a7 0f fd call 0xfd0fa766 17: 5b pop %rbx 18: 5d pop %rbp 19: e9 48 27 a4 06 jmp 0x6a42766 1e: e8 43 a7 0f fd call 0xfd0fa766 23: 48 8d 3d 8c d0 ec 0b lea 0xbecd08c(%rip),%rdi # 0xbecd0b6 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: e8 32 a7 0f fd call 0xfd0fa766 34: 5b pop %rbx 35: 5d pop %rbp 36: c3 ret 37: cc int3 38: cc int3 39: cc int3 3a: cc int3 3b: e8 26 a7 0f fd call 0xfd0fa766 --- 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 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