From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f199.google.com (mail-pl1-f199.google.com [209.85.214.199]) by kanga.kvack.org (Postfix) with ESMTP id 8B2E26B7F39 for ; Fri, 7 Sep 2018 12:18:36 -0400 (EDT) Received: by mail-pl1-f199.google.com with SMTP id a8-v6so7327328pla.10 for ; Fri, 07 Sep 2018 09:18:36 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id b1-v6si8778622pli.54.2018.09.07.09.18.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Sep 2018 09:18:35 -0700 (PDT) Subject: Re: BUG: bad usercopy in __check_object_size (2) References: <000000000000e16cba057549aab6@google.com> From: Tetsuo Handa Message-ID: <14d5bccf-f12d-0fc1-eddc-9fb24dc0cf14@I-love.SAKURA.ne.jp> Date: Sat, 8 Sep 2018 01:17:44 +0900 MIME-Version: 1.0 In-Reply-To: <000000000000e16cba057549aab6@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: keescook@chromium.org, keescook@google.com Cc: syzbot , crecklin@redhat.com, dvyukov@google.com, hpa@zytor.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, luto@kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, x86@kernel.org On 2018/09/08 0:29, syzbot wrote: > syzbot has found a reproducer for the following crash on: > > HEAD commit:A A A 28619527b8a7 Merge git://git.kernel.org/pub/scm/linux/kern.. > git tree:A A A A A A bpf > console output: https://syzkaller.appspot.com/x/log.txt?x=124e64d1400000 > kernel config:A https://syzkaller.appspot.com/x/.config?x=62e9b447c16085cf > dashboard link: https://syzkaller.appspot.com/bug?extid=a3c9d2673837ccc0f22b > compiler:A A A A A A gcc (GCC) 8.0.1 20180413 (experimental) > syz repro:A A A A A https://syzkaller.appspot.com/x/repro.syz?x=179f9cd1400000 > C reproducer:A A https://syzkaller.appspot.com/x/repro.c?x=11b3e8be400000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+a3c9d2673837ccc0f22b@syzkaller.appspotmail.com > > A entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x440479 > usercopy: Kernel memory overwrite attempt detected to spans multiple pages (offset 0, size 64)! Kees, is this because check_page_span() is failing to allow on-stack variable u8 opcodes[OPCODE_BUFSIZE]; which by chance crossed PAGE_SIZE boundary?