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=-13.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 62DD4C433DF for ; Tue, 21 Jul 2020 12:18:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F7FA21702 for ; Tue, 21 Jul 2020 12:18:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727972AbgGUMSa (ORCPT ); Tue, 21 Jul 2020 08:18:30 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:8345 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726715AbgGUMSa (ORCPT ); Tue, 21 Jul 2020 08:18:30 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id C43DCBD069A4045BE7D7; Tue, 21 Jul 2020 20:18:22 +0800 (CST) Received: from [127.0.0.1] (10.174.176.211) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Tue, 21 Jul 2020 20:18:11 +0800 Subject: Re: [PATCH] serial: 8250: fix null-ptr-deref in serial8250_start_tx() From: Yang Yingliang To: Greg KH CC: , , , Hanjun Guo , "Libin (Huawei)" References: <20200721143852.4058352-1-yangyingliang@huawei.com> <20200721104819.GA1678476@kroah.com> Message-ID: <571a38df-37a3-3680-bea0-b4698d4b417a@huawei.com> Date: Tue, 21 Jul 2020 20:18:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.176.211] X-CFilter-Loop: Reflected Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 2020/7/21 19:54, Yang Yingliang wrote: > > On 2020/7/21 18:48, Greg KH wrote: >> On Tue, Jul 21, 2020 at 02:38:52PM +0000, Yang Yingliang wrote: >>> I got null-ptr-deref in serial8250_start_tx(): >>> >>> [   78.114630] Unable to handle kernel NULL pointer dereference at >>> virtual address 0000000000000000 >>> [   78.123778] Mem abort info: >>> [   78.126560]   ESR = 0x86000007 >>> [   78.129603]   EC = 0x21: IABT (current EL), IL = 32 bits >>> [   78.134891]   SET = 0, FnV = 0 >>> [   78.137933]   EA = 0, S1PTW = 0 >>> [   78.141064] user pgtable: 64k pages, 48-bit VAs, >>> pgdp=00000027d41a8600 >>> [   78.147562] [0000000000000000] pgd=00000027893f0003, >>> p4d=00000027893f0003, pud=00000027893f0003, pmd=00000027c9a20003, >>> pte=0000000000000000 >>> [   78.160029] Internal error: Oops: 86000007 [#1] SMP >>> [   78.164886] Modules linked in: sunrpc vfat fat aes_ce_blk >>> crypto_simd cryptd aes_ce_cipher crct10dif_ce ghash_ce sha2_ce >>> sha256_arm64 sha1_ce ses enclosure sg sbsa_gwdt ipmi_ssif >>> spi_dw_mmio sch_fq_codel vhost_net tun vhost vhost_iotlb tap >>> ip_tables ext4 mbcache jbd2 ahci hisi_sas_v3_hw libahci >>> hisi_sas_main libsas hns3 scsi_transport_sas hclge libata >>> megaraid_sas ipmi_si hnae3 ipmi_devintf ipmi_msghandler br_netfilter >>> bridge stp llc nvme nvme_core xt_sctp sctp libcrc32c dm_mod nbd >>> [   78.207383] CPU: 11 PID: 23258 Comm: null-ptr Not tainted >>> 5.8.0-rc6+ #48 >>> [   78.214056] Hardware name: Huawei TaiShan 2280 V2/BC82AMDC, BIOS >>> 2280-V2 CS V3.B210.01 03/12/2020 >>> [   78.222888] pstate: 80400089 (Nzcv daIf +PAN -UAO BTYPE=--) >>> [   78.228435] pc : 0x0 >>> [   78.230618] lr : serial8250_start_tx+0x160/0x260 >>> [   78.235215] sp : ffff800062eefb80 >>> [   78.238517] x29: ffff800062eefb80 x28: 0000000000000fff >>> [   78.243807] x27: ffff800062eefd80 x26: ffff202fd83b3000 >>> [   78.249098] x25: ffff800062eefd80 x24: ffff202fd83b3000 >>> [   78.254388] x23: ffff002fc5e50be8 x22: 0000000000000002 >>> [   78.259679] x21: 0000000000000001 x20: 0000000000000000 >>> [   78.264969] x19: ffffa688827eecc8 x18: 0000000000000000 >>> [   78.270259] x17: 0000000000000000 x16: 0000000000000000 >>> [   78.275550] x15: ffffa68881bc67a8 x14: 00000000000002e6 >>> [   78.280841] x13: ffffa68881bc67a8 x12: 000000000000c539 >>> [   78.286131] x11: d37a6f4de9bd37a7 x10: ffffa68881cccff0 >>> [   78.291421] x9 : ffffa68881bc6000 x8 : ffffa688819daa88 >>> [   78.296711] x7 : ffffa688822a0f20 x6 : ffffa688819e0000 >>> [   78.302002] x5 : ffff800062eef9d0 x4 : ffffa68881e707a8 >>> [   78.307292] x3 : 0000000000000000 x2 : 0000000000000002 >>> [   78.312582] x1 : 0000000000000001 x0 : ffffa688827eecc8 >>> [   78.317873] Call trace: >>> [   78.320312]  0x0 >>> [   78.322147]  __uart_start.isra.9+0x64/0x78 >>> [   78.326229]  uart_start+0xb8/0x1c8 >>> [   78.329620]  uart_flush_chars+0x24/0x30 >>> [   78.333442]  n_tty_receive_buf_common+0x7b0/0xc30 >>> [   78.338128]  n_tty_receive_buf+0x44/0x2c8 >>> [   78.342122]  tty_ioctl+0x348/0x11f8 >>> [   78.345599]  ksys_ioctl+0xd8/0xf8 >>> [   78.348903]  __arm64_sys_ioctl+0x2c/0xc8 >>> [   78.352812]  el0_svc_common.constprop.2+0x88/0x1b0 >>> [   78.357583]  do_el0_svc+0x44/0xd0 >>> [   78.360887]  el0_sync_handler+0x14c/0x1d0 >>> [   78.364880]  el0_sync+0x140/0x180 >>> [   78.368185] Code: bad PC value >>> >>> SERIAL_PORT_DFNS is not defined on each arch, if it's not defined, >>> serial8250_set_defaults() won't be called in >>> serial8250_isa_init_ports(), >>> so the p->serial_in pointer won't be initialized, and it leads a >>> null-ptr-deref. >>> Fix this problem by calling serial8250_set_defaults() after init >>> uart port. >>> >>> Signed-off-by: Yang Yingliang >>> --- >>>   drivers/tty/serial/8250/8250_core.c | 2 +- >>>   1 file changed, 1 insertion(+), 1 deletion(-) >> Does this fix a specific commit, or has this issue always been present? >> What has caused it to happen now that no one else has seen this? > > I think it's always been present on the arch that not defined > SERIAL_PORT_DFNS. > > I got this on arm64 and here is the C reproducer: > > // autogenerated by syzkaller (https://github.com/google/syzkaller) > > #define _GNU_SOURCE > > #include > #include > #include > #include > #include > #include > #include > #include > > #ifndef __NR_ioctl > #define __NR_ioctl 29 > #endif > #ifndef __NR_mmap > #define __NR_mmap 222 > #endif > #ifndef __NR_openat > #define __NR_openat 56 > #endif > > uint64_t r[1] = {0xffffffffffffffff}; > > int main(void) > { >     syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1, 0); >     intptr_t res = 0; >     memcpy((void*)0x20000040, "/dev/ttyS3\000", 11); >     res = syscall(__NR_openat, 0xffffffffffffff9cul, 0x20000040ul, > 0x401ul, 0ul); >     if (res != -1) >         r[0] = res; >     syscall(__NR_ioctl, r[0], 0x5412ul, 0x20000080ul); >     return 0; > } > It's can be reproduced with CONFIG_SERIAL_8250_RUNTIME_UARTS=8 and by opening ttyS4 on x86_64. Because the size of SERIAL_PORT_DFNS is 4 and the pointers of ttyS4 ~ ttyS7 won't be initialized. [   49.427884] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [   49.432786] PGD 80000003d7573067 P4D 80000003d7573067 PUD 3d7526067 PMD 0 [   49.436944] Oops: 0010 [#1] SMP KASAN PTI [   49.439490] CPU: 1 PID: 2491 Comm: test Not tainted 4.19.90+ #1083 [   49.443437] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [   49.450233] RIP: 0010:          (null) [   49.452279] Code: Bad RIP value. [   49.454066] RSP: 0018:ffff8883d73a7880 EFLAGS: 00010093 [   49.457082] RAX: ffff8883d72d6000 RBX: ffffffff85e243a0 RCX: ffffffff820a062b [   49.460916] RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffffffff85e243a0 [   49.464490] RBP: 0000000000000002 R08: fffffbfff0bc4875 R09: fffffbfff0bc4874 [   49.467993] R10: fffffbfff0bc4874 R11: ffffffff85e243a3 R12: ffffffff85e245f6 [   49.471526] R13: ffffffff85e243f0 R14: 0000000000000000 R15: 0000000000000000 [   49.475192] FS:  0000000002064880(0000) GS:ffff8883eb240000(0000) knlGS:0000000000000000 [   49.479019] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [   49.481852] CR2: ffffffffffffffd6 CR3: 00000003d77a2006 CR4: 0000000000020ee0 [   49.485131] Call Trace: [   49.486278]  serial8250_start_tx+0x56c/0x9b0 [   49.488167]  __uart_start.isra.1+0x16a/0x1b0 [   49.490082]  uart_start+0x1a7/0x340 [   49.491650]  ? __uart_start.isra.1+0x1b0/0x1b0 [   49.493670]  ? __process_echoes+0x636/0x860 [   49.495540]  ? uart_start+0x340/0x340 [   49.497442]  n_tty_receive_buf_common+0x10ff/0x2460 [   49.499897]  ? n_tty_receive_buf2+0x40/0x40 [   49.501915]  tty_ioctl+0x6e1/0x1400 [   49.503629]  ? quarantine_put+0xb7/0x150 [   49.505474]  ? tty_vhangup+0x30/0x30 [   49.507237]  ? lockdep_hardirqs_on+0x290/0x560 [   49.509419]  ? __kasan_slab_free+0x1ce/0x230 [   49.511490]  ? kmem_cache_free+0xa6/0x2a0 [   49.513454]  ? putname+0xd4/0x110 [   49.515059]  ? do_sys_open+0x291/0x3f0 [   49.516888]  ? do_syscall_64+0x11c/0xe08 [   49.518795]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [   49.521359]  ? __lock_acquire+0x5eb/0x2e50 [   49.523278]  ? restore_nameidata+0x108/0x180 [   49.525242]  ? tty_vhangup+0x30/0x30 [   49.526895]  do_vfs_ioctl+0x1a5/0x1100 [   49.528608]  ? may_open_dev+0xd0/0xd0 [   49.530414]  ? ioctl_preallocate+0x1d0/0x1d0 [   49.532607]  ? putname+0xd4/0x110 [   49.534097]  ? rcu_read_lock_sched_held+0x114/0x130 [   49.536342]  ? kmem_cache_free+0x263/0x2a0 [   49.538450]  ? putname+0xd4/0x110 [   49.540036]  ? do_sys_open+0x1ec/0x3f0 [   49.541909]  ksys_ioctl+0x7c/0xa0 [   49.543458]  __x64_sys_ioctl+0x74/0xb0 [   49.545433]  ? lockdep_hardirqs_on+0x37c/0x560 [   49.547642]  do_syscall_64+0x11c/0xe08 [   49.549447]  ? syscall_return_slowpath+0x3a0/0x3a0 [   49.551741]  ? trace_hardirqs_on_thunk+0x1a/0x1c [   49.553810]  ? trace_hardirqs_off_caller+0x54/0x190 [   49.556125]  ? trace_hardirqs_off_thunk+0x1a/0x1c [   49.558453]  entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Thanks, > > Yang > >> >> thanks, >> >> greg k-h >> . > > .