From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B381C4321E for ; Mon, 5 Dec 2022 07:04:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231573AbiLEHEe (ORCPT ); Mon, 5 Dec 2022 02:04:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231572AbiLEHEc (ORCPT ); Mon, 5 Dec 2022 02:04:32 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D23DC767 for ; Sun, 4 Dec 2022 23:04:30 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C6C8860F85 for ; Mon, 5 Dec 2022 07:04:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67690C433C1; Mon, 5 Dec 2022 07:04:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670223869; bh=ew6SME2iZnd4VGhKxcng93VncjtjPCH9MqEPTJE39Bw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UfGk7p2SinwFxp843mB6ichZNpiHXEGiMfM5vIWo/x4hZ3xSWfIU/7L7e+Wc5t54v WzeidTI/eQ3yl+qpQOWZog+iVC1BH9dO9+KJKdvZxHHGzcx91VS8r4+qE7hhrfvyYA iQJyoH3mf1kqaH27vL4txGFFLppikW6eQtNd5DYTkZlY6ctQY+wKlgXKsLXeAUqgS2 5v+/RvEUCIIsiscejbC632/MOXcx5uVh4exwW7J+q6ioyCgeomjefHuGJTDRAlw47S AB0R8SNXTOSDAiS6urStCoAOYFSOAPM8m8lOr9mT3408ONGOLfLNgwphn3ZE74M8Qt kt4tNFHwpHKvQ== Date: Mon, 5 Dec 2022 09:04:24 +0200 From: Leon Romanovsky To: Nir Levy Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org Subject: Re: [PATCH] atm: Fix use-after-free bug in atm_dev_register() Message-ID: References: <20221203110924.7759-1-bhr166@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221203110924.7759-1-bhr166@gmail.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Dec 03, 2022 at 01:09:24PM +0200, Nir Levy wrote: > When device_register() return failed in atm_register_sysfs, > the program will return to atm_dev_register and will kfree > the device. As the comment of device_register() says, > put_device() needs to be used to give up the reference > in the error path. Using kfree instead triggers a UAF, > as shown by the following KASAN report, obtained by causing > device_register() to fail. This patch calls put_device instead > of kfree when atm_register_sysfs has failed, and call kfree > only when atm_proc_dev_register has failed. > > KASAN report details as below: > > [ 94.341664] BUG: KASAN: use-after-free in sysfs_kf_seq_show+0x306/0x440 > [ 94.341674] Read of size 8 at addr ffff88819a8a30e8 by task systemd-udevd/484 > > [ 94.341680] CPU: 3 PID: 484 Comm: systemd-udevd Tainted: G E 6.1.0-rc1+ #1 > [ 94.341684] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020 > [ 94.341703] Call Trace: > [ 94.341705] > [ 94.341707] dump_stack_lvl+0x49/0x63 > [ 94.341713] print_report+0x177/0x46e > [ 94.341717] ? kasan_complete_mode_report_info+0x7c/0x210 > [ 94.341720] ? sysfs_kf_seq_show+0x306/0x440 > [ 94.341753] kasan_report+0xb0/0x140 > [ 94.341757] ? sysfs_kf_seq_show+0x306/0x440 > [ 94.341760] __asan_report_load8_noabort+0x14/0x20 > [ 94.341763] sysfs_kf_seq_show+0x306/0x440 > [ 94.341766] kernfs_seq_show+0x145/0x1b0 > [ 94.341769] seq_read_iter+0x408/0x1080 > [ 94.341774] kernfs_fop_read_iter+0x3d5/0x540 > [ 94.341794] vfs_read+0x542/0x800 > [ 94.341797] ? kernel_read+0x130/0x130 > [ 94.341800] ? __kasan_check_read+0x11/0x20 > [ 94.341824] ? get_nth_filter.part.0+0x200/0x200 > [ 94.341828] ksys_read+0x116/0x220 > [ 94.341831] ? __ia32_sys_pwrite64+0x1f0/0x1f0 > [ 94.341849] ? __secure_computing+0x17c/0x2d0 > [ 94.341852] __x64_sys_read+0x72/0xb0 > [ 94.341875] do_syscall_64+0x59/0x90 > [ 94.341878] ? exc_page_fault+0x72/0xf0 > [ 94.341881] entry_SYSCALL_64_after_hwframe+0x63/0xcd > [ 94.341885] RIP: 0033:0x7fc391f14992 > [ 94.341888] Code: c0 e9 b2 fe ff ff 50 48 8d 3d fa b2 0c 00 e8 c5 1d 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 > [ 94.341891] RSP: 002b:00007ffe33fed818 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > [ 94.341896] RAX: ffffffffffffffda RBX: 0000000000001018 RCX: 00007fc391f14992 > [ 94.341898] RDX: 0000000000001018 RSI: 0000558a696b0880 RDI: 000000000000000e > [ 94.341900] RBP: 0000558a696b0880 R08: 0000000000000000 R09: 0000558a696b0880 > [ 94.341902] R10: 00007fc39201a300 R11: 0000000000000246 R12: 000000000000000e > [ 94.341904] R13: 0000000000001017 R14: 0000000000000002 R15: 00007ffe33fed840 > [ 94.341908] > > [ 94.341911] Allocated by task 2613: > [ 94.341914] kasan_save_stack+0x26/0x50 > [ 94.341932] kasan_set_track+0x25/0x40 > [ 94.341934] kasan_save_alloc_info+0x1e/0x30 > [ 94.341936] __kasan_kmalloc+0xb4/0xc0 > [ 94.341938] kmalloc_trace+0x4a/0xb0 > [ 94.341941] atm_dev_register+0x5d/0x700 [atm] > [ 94.341949] atmtcp_create+0x77/0x1f0 [atmtcp] > [ 94.341953] atmtcp_ioctl+0x12d/0xb9f [atmtcp] > [ 94.341957] do_vcc_ioctl+0xfe/0x640 [atm] > [ 94.341962] vcc_ioctl+0x10/0x20 [atm] > [ 94.341968] svc_ioctl+0x587/0x6c0 [atm] > [ 94.341973] sock_do_ioctl+0xd7/0x1e0 > [ 94.341977] sock_ioctl+0x1b5/0x560 > [ 94.341979] __x64_sys_ioctl+0x132/0x1b0 > [ 94.341981] do_syscall_64+0x59/0x90 > [ 94.341983] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > [ 94.341986] Freed by task 2613: > [ 94.341988] kasan_save_stack+0x26/0x50 > [ 94.341991] kasan_set_track+0x25/0x40 > [ 94.341993] kasan_save_free_info+0x2e/0x50 > [ 94.341995] ____kasan_slab_free+0x174/0x1e0 > [ 94.341997] __kasan_slab_free+0x12/0x20 > [ 94.342000] slab_free_freelist_hook+0xd0/0x1a0 > [ 94.342002] __kmem_cache_free+0x193/0x2c0 > [ 94.342005] kfree+0x79/0x120 > [ 94.342007] atm_dev_register.cold+0x46/0x64 [atm] > [ 94.342013] atmtcp_create+0x77/0x1f0 [atmtcp] > [ 94.342016] atmtcp_ioctl+0x12d/0xb9f [atmtcp] > [ 94.342020] do_vcc_ioctl+0xfe/0x640 [atm] > [ 94.342077] vcc_ioctl+0x10/0x20 [atm] > [ 94.342083] svc_ioctl+0x587/0x6c0 [atm] > [ 94.342088] sock_do_ioctl+0xd7/0x1e0 > [ 94.342091] sock_ioctl+0x1b5/0x560 > [ 94.342093] __x64_sys_ioctl+0x132/0x1b0 > [ 94.342095] do_syscall_64+0x59/0x90 > [ 94.342098] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > [ 94.342102] The buggy address belongs to the object at ffff88819a8a3000 which belongs to the cache kmalloc-1k of size 1024 > [ 94.342105] The buggy address is located 232 bytes inside of 1024-byte region [ffff88819a8a3000, ffff88819a8a3400) > > [ 94.342109] The buggy address belongs to the physical page: > [ 94.342111] page:0000000099993f0a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x19a8a0 > [ 94.342114] head:0000000099993f0a order:3 compound_mapcount:0 compound_pincount:0 > [ 94.342116] flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) > [ 94.342136] raw: 0017ffffc0010200 dead000000000100 dead000000000122 ffff888100042dc0 > [ 94.342138] raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 > [ 94.342139] page dumped because: kasan: bad access detected > > [ 94.342141] Memory state around the buggy address: > [ 94.342143] ffff88819a8a2f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [ 94.342145] ffff88819a8a3000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [ 94.342147] >ffff88819a8a3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [ 94.342148] ^ > [ 94.342150] ffff88819a8a3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > [ 94.342152] ffff88819a8a3180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > Signed-off-by: Nir Levy > --- > net/atm/resources.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) Please add target in patch title - {PATCH net] ... There is a need to add Fixes line too. > > diff --git a/net/atm/resources.c b/net/atm/resources.c > index 2b2d33eeaf20..9ec07d66783b 100644 > --- a/net/atm/resources.c > +++ b/net/atm/resources.c > @@ -112,12 +112,14 @@ struct atm_dev *atm_dev_register(const char *type, struct device *parent, > > if (atm_proc_dev_register(dev) < 0) { > pr_err("atm_proc_dev_register failed for dev %s\n", type); > + kfree(dev); > goto out_fail; > } > > if (atm_register_sysfs(dev, parent) < 0) { > pr_err("atm_register_sysfs failed for dev %s\n", type); > atm_proc_dev_deregister(dev); > + put_device(&dev->class_dev); The right fix is to change atm_register_sysfs() to call this put_device and worth to get rid from device_del() which should be replaced with device_unregister(). Thanks > goto out_fail; > } > > @@ -128,7 +130,6 @@ struct atm_dev *atm_dev_register(const char *type, struct device *parent, > return dev; > > out_fail: > - kfree(dev); > dev = NULL; > goto out; > } > -- > 2.34.1 >