Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936882AbdLSA6A (ORCPT ); Mon, 18 Dec 2017 19:58:00 -0500 Received: from mail-vk0-f67.google.com ([209.85.213.67]:33632 "EHLO mail-vk0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933276AbdLSA56 (ORCPT ); Mon, 18 Dec 2017 19:57:58 -0500 X-Google-Smtp-Source: ACJfBotF2PJxV7BDyjJJoBU94jNxO2M3clVPANqRoFxho4n+lCjjVs/oMopUokvf6FIOcsJqqO3aQVF0DTc4ao9uuQQ= MIME-Version: 1.0 In-Reply-To: <6a50d160-56d0-29f9-cfed-6c9202140b43@I-love.SAKURA.ne.jp> References: <001a113e9ca8a3affd05609d7ccf@google.com> <6a50d160-56d0-29f9-cfed-6c9202140b43@I-love.SAKURA.ne.jp> From: Kees Cook Date: Mon, 18 Dec 2017 16:57:57 -0800 X-Google-Sender-Auth: z6CdQ19OGEzO5dHJ6sl43FKEAjg Message-ID: Subject: Re: BUG: bad usercopy in memdup_user To: Tetsuo Handa Cc: Linux-MM , syzbot , David Windsor , keun-o.park@darkmatter.ae, Laura Abbott , LKML , Mark Rutland , Ingo Molnar , syzkaller-bugs@googlegroups.com, Will Deacon Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3765 Lines: 85 On Mon, Dec 18, 2017 at 6:22 AM, Tetsuo Handa wrote: > On 2017/12/18 22:40, syzbot wrote: >> Hello, >> >> syzkaller hit the following crash on 6084b576dca2e898f5c101baef151f7bfdbb606d >> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master >> compiler: gcc (GCC) 7.1.1 20170620 >> .config is attached >> Raw console output is attached. >> >> Unfortunately, I don't have any reproducer for this bug yet. >> >> > > This BUG is reporting > > [ 26.089789] usercopy: kernel memory overwrite attempt detected to 0000000022a5b430 (kmalloc-1024) (1024 bytes) > > line. But isn't 0000000022a5b430 strange for kmalloc(1024, GFP_KERNEL)ed kernel address? The address is hashed (see the %p threads for 4.15). There's something strange going on with the slab allocator (I haven't tracked it down yet, unfortunately). -Kees > >> netlink: 1 bytes leftover after parsing attributes in process `syz-executor5'. >> ------------[ cut here ]------------ >> kernel BUG at mm/usercopy.c:84! >> invalid opcode: 0000 [#1] SMP >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Modules linked in: >> CPU: 0 PID: 3943 Comm: syz-executor0 Not tainted 4.15.0-rc3-next-20171214+ #67 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >> RIP: 0010:report_usercopy mm/usercopy.c:76 [inline] >> RIP: 0010:__check_object_size+0x1e2/0x250 mm/usercopy.c:276 >> RSP: 0018:ffffc90000d6fca8 EFLAGS: 00010292 >> RAX: 0000000000000062 RBX: ffffffff82e57be7 RCX: ffffffff8123dede >> RDX: 0000000000006340 RSI: ffffc900036c9000 RDI: ffff88021fc136f8 >> RBP: ffffc90000d6fce0 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801e076dc50 >> R13: 0000000000000400 R14: 0000000000000000 R15: ffffffff82edf8a5 >> FS: 00007fe747e20700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000000002000bffa CR3: 00000001dbd02006 CR4: 00000000001626f0 >> DR0: 0000000020000000 DR1: 0000000000010000 DR2: 000000000000f004 >> DR3: 0000000000000000 DR6: 00000000fffe0ff3 DR7: 0000000000000600 >> Call Trace: >> check_object_size include/linux/thread_info.h:112 [inline] >> check_copy_size include/linux/thread_info.h:143 [inline] >> copy_from_user include/linux/uaccess.h:146 [inline] >> memdup_user+0x46/0x90 mm/util.c:168 >> kvm_arch_vcpu_ioctl+0xc85/0x1810 arch/x86/kvm/x86.c:3499 >> kvm_vcpu_ioctl+0xf3/0x820 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2715 >> vfs_ioctl fs/ioctl.c:46 [inline] >> do_vfs_ioctl+0xaf/0x840 fs/ioctl.c:686 >> SYSC_ioctl fs/ioctl.c:701 [inline] >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 >> entry_SYSCALL_64_fastpath+0x1f/0x96 >> RIP: 0033:0x452a09 >> RSP: 002b:00007fe747e1fc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 >> RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452a09 >> RDX: 0000000020ebec00 RSI: 000000004400ae8f RDI: 0000000000000019 >> RBP: 000000000000023b R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f0628 >> R13: 00000000ffffffff R14: 00007fe747e206d4 R15: 0000000000000000 >> Code: 7b e5 82 48 0f 44 da e8 8d 82 eb ff 48 8b 45 d0 4d 89 e9 4c 89 e1 4c 89 fa 48 89 de 48 c7 c7 a8 51 e6 82 49 89 c0 e8 76 b7 e3 ff <0f> 0b 48 c7 c0 43 51 e6 82 eb a1 48 c7 c0 53 51 e6 82 eb 98 48 >> RIP: report_usercopy mm/usercopy.c:76 [inline] RSP: ffffc90000d6fca8 >> RIP: __check_object_size+0x1e2/0x250 mm/usercopy.c:276 RSP: ffffc90000d6fca8 >> ---[ end trace 189465b430781fff ]--- >> Kernel panic - not syncing: Fatal exception >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Kernel Offset: disabled >> Rebooting in 86400 seconds.. -- Kees Cook Pixel Security