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 0581D2E7F04; Tue, 15 Jul 2025 13:32:58 +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=1752586378; cv=none; b=qDonKAIHTZfE/5Pix/zvyVE+EGVnDUihqqcD/6j6u5ynvVAi9YfpFVHn541xjYNoRRQy07KW2OjmgXpiJxu+2DbY3ogXErTtsQtA9G6GlYdHFMQ7hGfnFnqjPCrdAl47HGo0UOjEZj5w6wsumTvn53OoEnIk8zg1b9SHwtgv8uo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752586378; c=relaxed/simple; bh=bejBpjBEFSlyCiATKd8paEHKxYEg9wTCRoj7xoO/hgw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R/yooIco5O88ADMtoe0fiTYL7BIBSQ3IgtjRJp4UGxV+Ve5AvR4KXTie92BUvsQqCOdMs0P85a223M9tFsdF7PeJPGhpYW7eQyXErUmWQPp6I3CeBKZcNHZo+beP0vAsIZQLXgjfpXWhts9MGzcn/3jKAGSaln7svA4MJszisXY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=wVMfw7Hy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="wVMfw7Hy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DCE0C4CEE3; Tue, 15 Jul 2025 13:32:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752586377; bh=bejBpjBEFSlyCiATKd8paEHKxYEg9wTCRoj7xoO/hgw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wVMfw7HyrLpIhpwKz+jEr+qNgGXRAhyFK5CT0hfRrAj8MHna/i4SgdTHoprezToCI qFs2KZvHZo1k3jSglL4M8bTv2RzElVTBbrQltHoVLQwBdVX1uO1a4dmuAhJlXenf/m zmUGQecdr8jM5/EzvWrHQXhmR2Qn0u8WsAKyHXyA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+8bd335d2ad3b93e80715@syzkaller.appspotmail.com, Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 043/148] atm: Release atm_dev_mutex after removing procfs in atm_dev_deregister(). Date: Tue, 15 Jul 2025 15:12:45 +0200 Message-ID: <20250715130802.040724746@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250715130800.293690950@linuxfoundation.org> References: <20250715130800.293690950@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit a433791aeaea6e84df709e0b9584b9bbe040cd1c ] syzbot reported a warning below during atm_dev_register(). [0] Before creating a new device and procfs/sysfs for it, atm_dev_register() looks up a duplicated device by __atm_dev_lookup(). These operations are done under atm_dev_mutex. However, when removing a device in atm_dev_deregister(), it releases the mutex just after removing the device from the list that __atm_dev_lookup() iterates over. So, there will be a small race window where the device does not exist on the device list but procfs/sysfs are still not removed, triggering the splat. Let's hold the mutex until procfs/sysfs are removed in atm_dev_deregister(). [0]: proc_dir_entry 'atm/atmtcp:0' already registered WARNING: CPU: 0 PID: 5919 at fs/proc/generic.c:377 proc_register+0x455/0x5f0 fs/proc/generic.c:377 Modules linked in: CPU: 0 UID: 0 PID: 5919 Comm: syz-executor284 Not tainted 6.16.0-rc2-syzkaller-00047-g52da431bf03b #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:proc_register+0x455/0x5f0 fs/proc/generic.c:377 Code: 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 a2 01 00 00 48 8b 44 24 10 48 c7 c7 20 c0 c2 8b 48 8b b0 d8 00 00 00 e8 0c 02 1c ff 90 <0f> 0b 90 90 48 c7 c7 80 f2 82 8e e8 0b de 23 09 48 8b 4c 24 28 48 RSP: 0018:ffffc9000466fa30 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817ae248 RDX: ffff888026280000 RSI: ffffffff817ae255 RDI: 0000000000000001 RBP: ffff8880232bed48 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff888076ed2140 R13: dffffc0000000000 R14: ffff888078a61340 R15: ffffed100edda444 FS: 00007f38b3b0c6c0(0000) GS:ffff888124753000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f38b3bdf953 CR3: 0000000076d58000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: proc_create_data+0xbe/0x110 fs/proc/generic.c:585 atm_proc_dev_register+0x112/0x1e0 net/atm/proc.c:361 atm_dev_register+0x46d/0x890 net/atm/resources.c:113 atmtcp_create+0x77/0x210 drivers/atm/atmtcp.c:369 atmtcp_attach drivers/atm/atmtcp.c:403 [inline] atmtcp_ioctl+0x2f9/0xd60 drivers/atm/atmtcp.c:464 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159 sock_do_ioctl+0x115/0x280 net/socket.c:1190 sock_ioctl+0x227/0x6b0 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f38b3b74459 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f38b3b0c198 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f38b3bfe318 RCX: 00007f38b3b74459 RDX: 0000000000000000 RSI: 0000000000006180 RDI: 0000000000000005 RBP: 00007f38b3bfe310 R08: 65732f636f72702f R09: 65732f636f72702f R10: 65732f636f72702f R11: 0000000000000246 R12: 00007f38b3bcb0ac R13: 00007f38b3b0c1a0 R14: 0000200000000200 R15: 00007f38b3bcb03b Fixes: 64bf69ddff76 ("[ATM]: deregistration removes device from atm_devs list immediately") Reported-by: syzbot+8bd335d2ad3b93e80715@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/685316de.050a0220.216029.0087.GAE@google.com/ Tested-by: syzbot+8bd335d2ad3b93e80715@syzkaller.appspotmail.com Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250624214505.570679-1-kuni1840@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/atm/resources.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/net/atm/resources.c +++ b/net/atm/resources.c @@ -148,11 +148,10 @@ void atm_dev_deregister(struct atm_dev * */ mutex_lock(&atm_dev_mutex); list_del(&dev->dev_list); - mutex_unlock(&atm_dev_mutex); - atm_dev_release_vccs(dev); atm_unregister_sysfs(dev); atm_proc_dev_deregister(dev); + mutex_unlock(&atm_dev_mutex); atm_dev_put(dev); }