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=-12.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6C41AC433DF for ; Tue, 21 Jul 2020 19:11:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43A5C206E9 for ; Tue, 21 Jul 2020 19:11:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595358663; bh=OlmCX2de/3OxbnjjVkYRe3fW0bGYvRFlFzYJVgpLwhc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=kvokrrK0xvILwVLmHlODZpjvsbBDi67bvyYIgznyk+8UE64UUBYWp9azitQsOyJsI fTZJGfopixzXGl8bcBRYG/TtuvvioC5WH8c9nol/r66ZPHmcpQYSYruNLyG/tI90Td XYFwuZ8U4JCgddUF6/2mrZ55pTzFk+wH5Ui8PT5s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730297AbgGUTLC (ORCPT ); Tue, 21 Jul 2020 15:11:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:49202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726960AbgGUTLB (ORCPT ); Tue, 21 Jul 2020 15:11:01 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5521420672; Tue, 21 Jul 2020 19:11:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595358660; bh=OlmCX2de/3OxbnjjVkYRe3fW0bGYvRFlFzYJVgpLwhc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oebsANsy49BHYSke+RFZfL+t8n9fPF3BLcmXjooGoTG0jsIdJOoR64J+ZLLy47IIw LskPo93YTdGVsT4EvxwxMZTczZHKZjohsi+wTP4kSvZ55I+8g/Au8NzcHJ7t8ACfSd 7aUmnDA1it6zGeMJ/xCs3E48NCyZiutWg0gOrZGs= Date: Tue, 21 Jul 2020 21:11:08 +0200 From: Greg KH To: Yang Yingliang Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, jslaby@suse.com, Hanjun Guo , "Libin (Huawei)" Subject: Re: [PATCH] serial: 8250: fix null-ptr-deref in serial8250_start_tx() Message-ID: <20200721191108.GB2605882@kroah.com> References: <20200721143852.4058352-1-yangyingliang@huawei.com> <20200721104819.GA1678476@kroah.com> <571a38df-37a3-3680-bea0-b4698d4b417a@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <571a38df-37a3-3680-bea0-b4698d4b417a@huawei.com> Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Tue, Jul 21, 2020 at 08:18:11PM +0800, Yang Yingliang wrote: > > 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. Ah, good catch, yeah, that's not nice. I'll go queue this up now, thanks for the fix! greg k-h