From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C4A312D9EE5 for ; Mon, 10 Nov 2025 19:12:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762801920; cv=none; b=J3gM1OcWvhpP5BarohvEg3duR78Fd65xJvwP1g4HG0ntLmXn6yQwQxzicDV1Vg5vVoxKCkoKkPN9P/+iyx36DnW2kphEW6OJh90ZS5wAT9rpLM6vUegiEumMi8y9h6k6FcSOStFKyeUyNToLmLsSDD/wuFOIXimYDv6nGWSwuZs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762801920; c=relaxed/simple; bh=CJda8HcSRCgLx3iaVDT4cCr+lyNFyU/yT5bJQwPSZN0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hhh+3p5W7VcKT/k9uT9E4+F49JVcBRbzkynuZndTPWfaTJDWCfqu8L+IQiGZdTxLbj0kdQ8TVOx3F5xMMikkBGhQT6+18Fhl6EMwEx5fEdjYkQNd0feWei8zishJ35+cMFN3HCC+Phb5IJUCONFl7fz3G4om5iWfniY/crw8lLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uluihQ9D; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uluihQ9D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79817C4CEF5; Mon, 10 Nov 2025 19:11:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762801920; bh=CJda8HcSRCgLx3iaVDT4cCr+lyNFyU/yT5bJQwPSZN0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uluihQ9DEtiDN3rmXPMuBjYsT5IeFzRtiFu2FB+x1M0XZTC2ErUC4sKETsSAIOq5g B8Itt7hLTL9qIDdGWrrcbCOj7uSPtB8zlTeA+bRijc5bRrX99XFu6oYJWlKEzASk6Q Rr1h0G1QTlApjh45AAkryaW9wlab4yXWqLJnraNA4rLHNqjE9L8oVKH8vHCO4c4nt9 5KtgBHGCz6dR/3uOAV3cEbUI9CnzdIwXjSyqTaFt4NBeEY4hED/PQYwxzd6Peo5+kq 4Zj/ZPxANRldLiYnX2hVRcyPLR7JULdZsojB1xk08qNgTvrAd9WCnvELysXPNptsP2 zdtt0jituopkA== Date: Mon, 10 Nov 2025 19:11:56 +0000 From: Simon Horman To: Kuniyuki Iwashima Cc: Jon Maloy , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Hoang Le , Kuniyuki Iwashima , netdev@vger.kernel.org, tipc-discussion@lists.sourceforge.net, syzbot+d7dad7fd4b3921104957@syzkaller.appspotmail.com Subject: Re: [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self(). Message-ID: References: <20251107064038.2361188-1-kuniyu@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251107064038.2361188-1-kuniyu@google.com> On Fri, Nov 07, 2025 at 06:40:25AM +0000, Kuniyuki Iwashima wrote: > syzbot reported use-after-free of tipc_net(net)->monitors[] > in tipc_mon_reinit_self(). [0] > > The array is protected by RTNL, but tipc_mon_reinit_self() > iterates over it without RTNL. > > tipc_mon_reinit_self() is called from tipc_net_finalize(), > which is always under RTNL except for tipc_net_finalize_work(). > > Let's hold RTNL in tipc_net_finalize_work(). > > [0]: > BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 > Read of size 1 at addr ffff88805eae1030 by task kworker/0:7/5989 > > CPU: 0 UID: 0 PID: 5989 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)} > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 > Workqueue: events tipc_net_finalize_work > Call Trace: > > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:378 [inline] > print_report+0xca/0x240 mm/kasan/report.c:482 > kasan_report+0x118/0x150 mm/kasan/report.c:595 > __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:568 > kasan_check_byte include/linux/kasan.h:399 [inline] > lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 > rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline] > rwbase_rtmutex_lock_state kernel/locking/spinlock_rt.c:160 [inline] > rwbase_write_lock+0xd3/0x7e0 kernel/locking/rwbase_rt.c:244 > rt_write_lock+0x76/0x110 kernel/locking/spinlock_rt.c:243 > write_lock_bh include/linux/rwlock_rt.h:99 [inline] > tipc_mon_reinit_self+0x79/0x430 net/tipc/monitor.c:718 > tipc_net_finalize+0x115/0x190 net/tipc/net.c:140 > process_one_work kernel/workqueue.c:3236 [inline] > process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 > worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 > kthread+0x70e/0x8a0 kernel/kthread.c:463 > ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > > Allocated by task 6089: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 > poison_kmalloc_redzone mm/kasan/common.c:388 [inline] > __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405 > kasan_kmalloc include/linux/kasan.h:260 [inline] > __kmalloc_cache_noprof+0x1a8/0x320 mm/slub.c:4407 > kmalloc_noprof include/linux/slab.h:905 [inline] > kzalloc_noprof include/linux/slab.h:1039 [inline] > tipc_mon_create+0xc3/0x4d0 net/tipc/monitor.c:657 > tipc_enable_bearer net/tipc/bearer.c:357 [inline] > __tipc_nl_bearer_enable+0xe16/0x13f0 net/tipc/bearer.c:1047 > __tipc_nl_compat_doit net/tipc/netlink_compat.c:371 [inline] > tipc_nl_compat_doit+0x3bc/0x5f0 net/tipc/netlink_compat.c:393 > tipc_nl_compat_handle net/tipc/netlink_compat.c:-1 [inline] > tipc_nl_compat_recv+0x83c/0xbe0 net/tipc/netlink_compat.c:1321 > genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115 > genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] > genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 > netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 > genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 > netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] > netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346 > netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 > sock_sendmsg_nosec net/socket.c:714 [inline] > __sock_sendmsg+0x21c/0x270 net/socket.c:729 > ____sys_sendmsg+0x508/0x820 net/socket.c:2614 > ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 > __sys_sendmsg net/socket.c:2700 [inline] > __do_sys_sendmsg net/socket.c:2705 [inline] > __se_sys_sendmsg net/socket.c:2703 [inline] > __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703 > 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 > > Freed by task 6088: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 > kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 > poison_slab_object mm/kasan/common.c:243 [inline] > __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275 > kasan_slab_free include/linux/kasan.h:233 [inline] > slab_free_hook mm/slub.c:2422 [inline] > slab_free mm/slub.c:4695 [inline] > kfree+0x195/0x550 mm/slub.c:4894 > tipc_l2_device_event+0x380/0x650 net/tipc/bearer.c:-1 > 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] > unregister_netdevice_many_notify+0x14d7/0x1fe0 net/core/dev.c:12166 > unregister_netdevice_many net/core/dev.c:12229 [inline] > unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12073 > unregister_netdevice include/linux/netdevice.h:3385 [inline] > __tun_detach+0xe4d/0x1620 drivers/net/tun.c:621 > tun_detach drivers/net/tun.c:637 [inline] > tun_chr_close+0x10d/0x1c0 drivers/net/tun.c:3433 > __fput+0x458/0xa80 fs/file_table.c:468 > task_work_run+0x1d4/0x260 kernel/task_work.c:227 > resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] > exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43 > exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] > syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] > syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] > do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Fixes: 46cb01eeeb86 ("tipc: update mon's self addr when node addr generated") > Reported-by: syzbot+d7dad7fd4b3921104957@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/690c323a.050a0220.baf87.007f.GAE@google.com/ > Signed-off-by: Kuniyuki Iwashima > --- > v2: Wrap tipc_net_finalize_work() with RTNL (Jakub) > v1: https://lore.kernel.org/netdev/20251106053309.401275-1-kuniyu@google.com/ Thanks Iwashima-san, I agree with the analysis above. Reviewed-by: Simon Horman