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=-13.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 0F652C2BA13 for ; Wed, 1 Apr 2020 07:04:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAFCC20719 for ; Wed, 1 Apr 2020 07:04:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="s2hg2htp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731910AbgDAHEZ (ORCPT ); Wed, 1 Apr 2020 03:04:25 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:43286 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731850AbgDAHEX (ORCPT ); Wed, 1 Apr 2020 03:04:23 -0400 Received: by mail-qk1-f194.google.com with SMTP id o10so25974779qki.10 for ; Wed, 01 Apr 2020 00:04:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=El2QKEKkvpg6iAWNInUHfxZbiEumudKWoBkgubLXWZA=; b=s2hg2htp5hxoEWqtFZrybH253BnBuQZC/c0U+8hvebmFiQtkag4z9EhA/VJNkOnXwe y+obuAWSIsWOpse5qXc3sud4KwnYfQTkDRFwqGJ1xIs7a7Ghs5Dwx9vQcZ1gEER9tyWY Q17Anv/lWhT7McaHWAQE/1HeSSFxApEeLbcLPdk1v7TKw6/DsH/bzMHi+ckTG97/hvcm I/qEnik5ZAcvV+h71O0P/xwU6gqLXsRLKB7/3VZXuVzRW8Mg4JSAtvzTyA9f7cLBME8l 5faDnwVDBpgKekEzmm5yMzZemyunI3qEBP48FzW51grEdzWJM3STVyF6doy8SvFx6+gp Sy6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=El2QKEKkvpg6iAWNInUHfxZbiEumudKWoBkgubLXWZA=; b=Kl1gAGpcs4Gnbt4Q/y4RlcOncvInwI3F2qJ3akPWBagn+xkDaWehjxf3AJLON+xsDj 36sQmv5pajpx1h7gJTRMbh0Tb627/EeikZvLemeG9mHk4Xfi40ZCjuclKb3QTuVsgFPc uuH/Kd8kh6ASeXhFiK5fGPv4b/1RSBP3ySqz0XWIAwT0uKu7Vn90REfc6/TLZ7TG75eD d/dix/qRFSEy1kd6O31CM7GOaJJIAhLFOJAXfifphVpDJebdHsEVqx+Am/OPi9ETD66v z+ypUa+tOQiBryE6rPTziJlaDFd4HBlivxL8TNZRgztKh97sO2/Dw+lq+SCGa3SPQ09K PeOA== X-Gm-Message-State: ANhLgQ28UrcflNU7UjSalV9Te1AyV5CD/KAu3QBROhCT9Unw4Dc6sgdc 3KtOi59QQfU7QGo7FX1IBCJyUVBgmWgz6AZ++GtqDA== X-Google-Smtp-Source: ADFU+vuy057DXLdO0dRHxTb9pVmk5NJNDwnCh8OY/djQ716fL1PpAmxCQddIqpx3KaHqqAo9ftsvkmk929QeZ3/HlEo= X-Received: by 2002:a37:664d:: with SMTP id a74mr8311709qkc.256.1585724661328; Wed, 01 Apr 2020 00:04:21 -0700 (PDT) MIME-Version: 1.0 References: <0000000000009d5cef05a22baa95@google.com> <20200331202706.GA127606@gmail.com> In-Reply-To: <20200331202706.GA127606@gmail.com> From: Dmitry Vyukov Date: Wed, 1 Apr 2020 09:04:10 +0200 Message-ID: Subject: Re: KCSAN: data-race in glue_cbc_decrypt_req_128bit / glue_cbc_decrypt_req_128bit To: Eric Biggers Cc: syzbot , Borislav Petkov , David Miller , Marco Elver , Herbert Xu , "H. Peter Anvin" , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , LKML , Ingo Molnar , syzkaller-bugs , Thomas Gleixner , "the arch/x86 maintainers" Content-Type: text/plain; charset="UTF-8" Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Tue, Mar 31, 2020 at 10:27 PM Eric Biggers wrote: > > On Tue, Mar 31, 2020 at 12:35:13PM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: b12d66a6 mm, kcsan: Instrument SLAB free with ASSERT_EXCLU.. > > git tree: https://github.com/google/ktsan.git kcsan > > console output: https://syzkaller.appspot.com/x/log.txt?x=111f0865e00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=10bc0131c4924ba9 > > dashboard link: https://syzkaller.appspot.com/bug?extid=6a6bca8169ffda8ce77b > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+6a6bca8169ffda8ce77b@syzkaller.appspotmail.com > > > > ================================================================== > > BUG: KCSAN: data-race in glue_cbc_decrypt_req_128bit / glue_cbc_decrypt_req_128bit > > > > write to 0xffff88809966e128 of 8 bytes by task 24119 on cpu 0: > > u128_xor include/crypto/b128ops.h:67 [inline] > > glue_cbc_decrypt_req_128bit+0x396/0x460 arch/x86/crypto/glue_helper.c:144 > > cbc_decrypt+0x26/0x40 arch/x86/crypto/serpent_avx2_glue.c:152 > > crypto_skcipher_decrypt+0x65/0x90 crypto/skcipher.c:652 > > _skcipher_recvmsg crypto/algif_skcipher.c:142 [inline] > > skcipher_recvmsg+0x7fa/0x8c0 crypto/algif_skcipher.c:161 > > skcipher_recvmsg_nokey+0x5e/0x80 crypto/algif_skcipher.c:279 > > sock_recvmsg_nosec net/socket.c:886 [inline] > > sock_recvmsg net/socket.c:904 [inline] > > sock_recvmsg+0x92/0xb0 net/socket.c:900 > > ____sys_recvmsg+0x167/0x3a0 net/socket.c:2566 > > ___sys_recvmsg+0xb2/0x100 net/socket.c:2608 > > __sys_recvmsg+0x9d/0x160 net/socket.c:2642 > > __do_sys_recvmsg net/socket.c:2652 [inline] > > __se_sys_recvmsg net/socket.c:2649 [inline] > > __x64_sys_recvmsg+0x51/0x70 net/socket.c:2649 > > do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > > read to 0xffff88809966e128 of 8 bytes by task 24118 on cpu 1: > > u128_xor include/crypto/b128ops.h:67 [inline] > > glue_cbc_decrypt_req_128bit+0x37c/0x460 arch/x86/crypto/glue_helper.c:144 > > cbc_decrypt+0x26/0x40 arch/x86/crypto/serpent_avx2_glue.c:152 > > crypto_skcipher_decrypt+0x65/0x90 crypto/skcipher.c:652 > > _skcipher_recvmsg crypto/algif_skcipher.c:142 [inline] > > skcipher_recvmsg+0x7fa/0x8c0 crypto/algif_skcipher.c:161 > > skcipher_recvmsg_nokey+0x5e/0x80 crypto/algif_skcipher.c:279 > > sock_recvmsg_nosec net/socket.c:886 [inline] > > sock_recvmsg net/socket.c:904 [inline] > > sock_recvmsg+0x92/0xb0 net/socket.c:900 > > ____sys_recvmsg+0x167/0x3a0 net/socket.c:2566 > > ___sys_recvmsg+0xb2/0x100 net/socket.c:2608 > > __sys_recvmsg+0x9d/0x160 net/socket.c:2642 > > __do_sys_recvmsg net/socket.c:2652 [inline] > > __se_sys_recvmsg net/socket.c:2649 [inline] > > __x64_sys_recvmsg+0x51/0x70 net/socket.c:2649 > > do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > > Reported by Kernel Concurrency Sanitizer on: > > CPU: 1 PID: 24118 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > ================================================================== > > > > I think this is a problem for almost all the crypto code. Due to AF_ALG, both > the source and destination buffers can be userspace pages that were gotten with > get_user_pages(). Such pages can be concurrently modified, not just by the > kernel but also by userspace. > > I'm not sure what can be done about this. Oh, I thought it's something more serious like a shared crypto object. Thanks for debugging. I think I've seen this before in another context (b/149818448): BUG: KCSAN: data-race in copyin / copyin write to 0xffff888103c8b000 of 4096 bytes by task 20917 on cpu 0: instrument_copy_from_user include/linux/instrumented.h:106 [inline] copyin+0xab/0xc0 lib/iov_iter.c:151 copy_page_from_iter_iovec lib/iov_iter.c:296 [inline] copy_page_from_iter+0x23f/0x5f0 lib/iov_iter.c:942 process_vm_rw_pages mm/process_vm_access.c:46 [inline] process_vm_rw_single_vec mm/process_vm_access.c:120 [inline] process_vm_rw_core.isra.0+0x448/0x820 mm/process_vm_access.c:218 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286 __do_sys_process_vm_writev mm/process_vm_access.c:308 [inline] __se_sys_process_vm_writev mm/process_vm_access.c:303 [inline] __x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:303 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x44/0xa9 write to 0xffff888103c8b000 of 4096 bytes by task 20918 on cpu 1: instrument_copy_from_user include/linux/instrumented.h:106 [inline] copyin+0xab/0xc0 lib/iov_iter.c:151 copy_page_from_iter_iovec lib/iov_iter.c:296 [inline] copy_page_from_iter+0x23f/0x5f0 lib/iov_iter.c:942 process_vm_rw_pages mm/process_vm_access.c:46 [inline] process_vm_rw_single_vec mm/process_vm_access.c:120 [inline] process_vm_rw_core.isra.0+0x448/0x820 mm/process_vm_access.c:218 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286 __do_sys_process_vm_writev mm/process_vm_access.c:308 [inline] __se_sys_process_vm_writev mm/process_vm_access.c:303 [inline] __x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:303 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Marco, I think we need to ignore all memory that comes from get_user_pages() somehow. Either not set watchpoints at all, or perhaps filter them out later if the check is not totally free.