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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A520C4360F for ; Thu, 14 Mar 2019 08:57:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10471217F5 for ; Thu, 14 Mar 2019 08:57:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727306AbfCNI50 (ORCPT ); Thu, 14 Mar 2019 04:57:26 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:51158 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726421AbfCNI50 (ORCPT ); Thu, 14 Mar 2019 04:57:26 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 0467834CF02955A3142D; Thu, 14 Mar 2019 16:57:23 +0800 (CST) Received: from localhost (10.177.31.96) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.408.0; Thu, 14 Mar 2019 16:57:16 +0800 From: Yue Haibing To: , , , , , CC: , , , , YueHaibing Subject: [PATCH v2] proc/sysctl: Fix NULL pointer dereference in put_links Date: Thu, 14 Mar 2019 16:55:27 +0800 Message-ID: <20190314085527.13244-1-yuehaibing@huawei.com> X-Mailer: git-send-email 2.10.2.windows.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.177.31.96] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: YueHaibing Syzkaller report this: kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN PTI CPU: 1 PID: 5373 Comm: syz-executor.0 Not tainted 5.0.0-rc8+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 RIP: 0010:put_links+0x101/0x440 fs/proc/proc_sysctl.c:1599 Code: 00 0f 85 3a 03 00 00 48 8b 43 38 48 89 44 24 20 48 83 c0 38 48 89 c2 48 89 44 24 28 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 fe 02 00 00 48 8b 74 24 20 48 c7 c7 60 2a 9d 91 RSP: 0018:ffff8881d828f238 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff8881e01b1140 RCX: ffffffff8ee98267 RDX: 0000000000000007 RSI: ffffc90001479000 RDI: ffff8881e01b1178 RBP: dffffc0000000000 R08: ffffed103ee27259 R09: ffffed103ee27259 R10: 0000000000000001 R11: ffffed103ee27258 R12: fffffffffffffff4 R13: 0000000000000006 R14: ffff8881f59838c0 R15: dffffc0000000000 FS: 00007f072254f700(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fff8b286668 CR3: 00000001f0542002 CR4: 00000000007606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: drop_sysctl_table+0x152/0x9f0 fs/proc/proc_sysctl.c:1629 get_subdir fs/proc/proc_sysctl.c:1022 [inline] __register_sysctl_table+0xd65/0x1090 fs/proc/proc_sysctl.c:1335 ? 0xffffffffc1a18000 br_netfilter_init+0xbc/0x1000 [br_netfilter] ? 0xffffffffc1a18000 ? 0xffffffffc1a18000 do_one_initcall+0xfa/0x5ca init/main.c:887 do_init_module+0x204/0x5f6 kernel/module.c:3460 load_module+0x66b2/0x8570 kernel/module.c:3808 __do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902 do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x462e99 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f072254ec58 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99 RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000003 RBP: 00007f072254ec70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f072254f6bc R13: 00000000004bcefa R14: 00000000006f6fb0 R15: 0000000000000004 Modules linked in: br_netfilter(+) dvb_usb_dibusb_mc_common dib3000mc dibx000_common dvb_usb_dibusb_common dvb_usb_dw2102 dvb_usb classmate_laptop palmas_regulator cn videobuf2_v4l2 v4l2_common snd_soc_bd28623 mptbase snd_usb_usx2y snd_usbmidi_lib snd_rawmidi wmi libnvdimm lockd sunrpc grace rc_kworld_pc150u rc_core rtc_da9063 sha1_ssse3 i2c_cros_ec_tunnel adxl34x_spi adxl34x nfnetlink lib80211 i5500_temp dvb_as102 dvb_core videobuf2_common videodev media videobuf2_vmalloc videobuf2_memops udc_core lnbp22 leds_lp3952 hid_roccat_ryos s1d13xxxfb mtd vport_geneve openvswitch nf_conncount nf_nat_ipv6 nsh geneve udp_tunnel ip6_udp_tunnel snd_soc_mt6351 sis_agp phylink snd_soc_adau1761_spi snd_soc_adau1761 snd_soc_adau17x1 snd_soc_core snd_pcm_dmaengine ac97_bus snd_compress snd_soc_adau_utils snd_soc_sigmadsp_regmap snd_soc_sigmadsp raid_class hid_roccat_konepure hid_roccat_common hid_roccat c2port_duramar2150 core mdio_bcm_unimac iptable_security iptable_raw iptable_mangle iptable_nat nf_nat_ipv4 nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter bpfilter ip6_vti ip_vti ip_gre ipip sit tunnel4 ip_tunnel hsr veth netdevsim devlink vxcan batman_adv cfg80211 rfkill chnl_net caif nlmon dummy team bonding vcan bridge stp llc ip6_gre gre ip6_tunnel tunnel6 tun crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel joydev mousedev ide_pci_generic piix aesni_intel aes_x86_64 ide_core crypto_simd atkbd cryptd glue_helper serio_raw ata_generic pata_acpi i2c_piix4 floppy sch_fq_codel ip_tables x_tables ipv6 [last unloaded: lm73] Dumping ftrace buffer: (ftrace buffer empty) ---[ end trace 770020de38961fd0 ]--- A new dir entry can be created in get_subdir and its 'header->parent' is set to NULL. Only after insert_header success, it will be set to 'dir', otherwise 'header->parent' is set to NULL and drop_sysctl_table is called. However in err handling path of get_subdir, drop_sysctl_table also be called on 'new->header' regardless its value of parent pointer. Then put_links is called, which triggers NULL-ptr deref when access member of header->parent. In fact we have multiple error paths which call drop_sysctl_table() there, upon failure on insert_links() we also call drop_sysctl_table().And even in the successful case on __register_sysctl_table() we still always call drop_sysctl_table().This patch fix it. Reported-by: Hulk Robot Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets") Signed-off-by: YueHaibing --- v2: fix commit log --- fs/proc/proc_sysctl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 4d598a3..4c2a05a 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -1626,7 +1626,8 @@ static void drop_sysctl_table(struct ctl_table_header *header) if (--header->nreg) return; - put_links(header); + if (parent) + put_links(header); start_unregistering(header); if (!--header->count) kfree_rcu(header, rcu); -- 2.7.0