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=-7.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 42E97C43331 for ; Tue, 31 Mar 2020 20:27:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19B55208E0 for ; Tue, 31 Mar 2020 20:27:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585686430; bh=KBJwO6H6Y0CusLpsPnIlkDyiEbM5ompx0TxNHV6EnzM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=t/cL7wW73KbSWJurl2/4RhoHffWNVIm8DvHN3IuOt4XZGhtanVZRbrSsOpsvyGRdF vrV/EjfuVrs5LfVMmATMtcXxkY1wy1MO8IcJFTcZZhiXg1ZaGZAqIFDG0gTxT8otHb kC8KFkf5mXPhFonLzQntRd/ur00SiRDJXZqn70tk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729941AbgCaU1J (ORCPT ); Tue, 31 Mar 2020 16:27:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:55224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727852AbgCaU1J (ORCPT ); Tue, 31 Mar 2020 16:27:09 -0400 Received: from gmail.com (unknown [104.132.1.76]) (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 0A44020757; Tue, 31 Mar 2020 20:27:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585686428; bh=KBJwO6H6Y0CusLpsPnIlkDyiEbM5ompx0TxNHV6EnzM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O/twBmAHYyNn1uDHoUVUd38Q6xNXNUbnyriuOKsOYdno07+7Wr65zcI/9Lstpd8KL EcYuKqK+nnNt6EbAE0kaWadIXzTqN1HlHCKawd/ldOPlouz0ne5ZREr4Unn3dqsExI iL2sQFXTDdDWOn6Ao21a0DgybA48ITA4UcofHjZI= Date: Tue, 31 Mar 2020 13:27:06 -0700 From: Eric Biggers To: syzbot Cc: bp@alien8.de, davem@davemloft.net, elver@google.com, herbert@gondor.apana.org.au, hpa@zytor.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, x86@kernel.org Subject: Re: KCSAN: data-race in glue_cbc_decrypt_req_128bit / glue_cbc_decrypt_req_128bit Message-ID: <20200331202706.GA127606@gmail.com> References: <0000000000009d5cef05a22baa95@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000009d5cef05a22baa95@google.com> User-Agent: Mutt/1.12.2 (2019-09-21) 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 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. - Eric