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 9DB1FC433E3 for ; Tue, 21 Jul 2020 11:55:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 825FC20792 for ; Tue, 21 Jul 2020 11:55:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726919AbgGULzF (ORCPT ); Tue, 21 Jul 2020 07:55:05 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:7810 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726266AbgGULzE (ORCPT ); Tue, 21 Jul 2020 07:55:04 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id DE71D5C1C5211E8B8AC4; Tue, 21 Jul 2020 19:55:01 +0800 (CST) Received: from [127.0.0.1] (10.174.176.211) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.487.0; Tue, 21 Jul 2020 19:54:52 +0800 Subject: Re: [PATCH] serial: 8250: fix null-ptr-deref in serial8250_start_tx() To: Greg KH CC: , , , Hanjun Guo , "Libin (Huawei)" References: <20200721143852.4058352-1-yangyingliang@huawei.com> <20200721104819.GA1678476@kroah.com> From: Yang Yingliang Message-ID: Date: Tue, 21 Jul 2020 19:54:51 +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: <20200721104819.GA1678476@kroah.com> 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 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; } Thanks, Yang > > thanks, > > greg k-h > .