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=-5.4 required=3.0 tests=FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 6D7BBC2BD09 for ; Mon, 9 Dec 2019 06:21:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40A562071E for ; Mon, 9 Dec 2019 06:21:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727222AbfLIGVM (ORCPT ); Mon, 9 Dec 2019 01:21:12 -0500 Received: from mail-io1-f70.google.com ([209.85.166.70]:51799 "EHLO mail-io1-f70.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id 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MIME-Version: 1.0 X-Received: by 2002:a92:178f:: with SMTP id 15mr25681536ilx.219.1575872469640; Sun, 08 Dec 2019 22:21:09 -0800 (PST) Date: Sun, 08 Dec 2019 22:21:09 -0800 In-Reply-To: <0000000000000b284d059906e13e@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000c3afe805993f6657@google.com> Subject: Re: KASAN: use-after-free Read in n_tty_receive_buf_common From: syzbot To: gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot has found a reproducer for the following crash on: HEAD commit: 9455d25f Merge tag 'ntb-5.5' of git://github.com/jonmason/.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=174b042ae00000 kernel config: https://syzkaller.appspot.com/x/.config?x=7a3b8f5088d4043a dashboard link: https://syzkaller.appspot.com/bug?extid=59997e8d5cbdc486e6f6 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c641dae00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=110d477ae00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+59997e8d5cbdc486e6f6@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in n_tty_check_throttle drivers/tty/n_tty.c:266 [inline] BUG: KASAN: use-after-free in n_tty_receive_buf_common+0x270f/0x2b70 drivers/tty/n_tty.c:1761 Read of size 1 at addr ffff88809f900b01 by task syz-executor920/9030 CPU: 1 PID: 9030 Comm: syz-executor920 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:639 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132 n_tty_check_throttle drivers/tty/n_tty.c:266 [inline] n_tty_receive_buf_common+0x270f/0x2b70 drivers/tty/n_tty.c:1761 n_tty_receive_buf2+0x34/0x40 drivers/tty/n_tty.c:1777 tty_ldisc_receive_buf+0xad/0x1c0 drivers/tty/tty_buffer.c:461 paste_selection+0x1ff/0x460 drivers/tty/vt/selection.c:372 tioclinux+0x133/0x480 drivers/tty/vt/vt.c:3044 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441309 Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fffea28a108 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441309 RDX: 0000000020000000 RSI: 000000000000541c RDI: 0000000000000003 RBP: 0000000000012d00 R08: 000000000000000d R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402080 R13: 0000000000402110 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 9027: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x163/0x770 mm/slab.c:3665 kmalloc_array include/linux/slab.h:598 [inline] set_selection_kernel+0x872/0x13b0 drivers/tty/vt/selection.c:305 set_selection_user+0x95/0xd9 drivers/tty/vt/selection.c:177 tioclinux+0x11c/0x480 drivers/tty/vt/vt.c:3039 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9028: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:335 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 set_selection_kernel+0x88f/0x13b0 drivers/tty/vt/selection.c:312 set_selection_user+0x95/0xd9 drivers/tty/vt/selection.c:177 tioclinux+0x11c/0x480 drivers/tty/vt/vt.c:3039 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88809f900b00 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 1 bytes inside of 96-byte region [ffff88809f900b00, ffff88809f900b60) The buggy address belongs to the page: page:ffffea00027e4000 refcount:1 mapcount:0 mapping:ffff8880aa400540 index:0x0 raw: 00fffe0000000200 ffffea0002871bc8 ffffea00027dc148 ffff8880aa400540 raw: 0000000000000000 ffff88809f900000 0000000100000020 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809f900a00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ffff88809f900a80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc > ffff88809f900b00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88809f900b80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88809f900c00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ==================================================================