From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752371AbeEQQ2k (ORCPT ); Thu, 17 May 2018 12:28:40 -0400 Received: from mail-io0-f193.google.com ([209.85.223.193]:45874 "EHLO mail-io0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396AbeEQQ2i (ORCPT ); Thu, 17 May 2018 12:28:38 -0400 X-Google-Smtp-Source: AB8JxZoLlN+dnWS3LFn3Y7tzrrHVUGv53R873YUTs6c9LT5rqzZci1zgN7JD1RTbYpNvePXDWidRmD59re4v53JG6H4= MIME-Version: 1.0 From: Kyungtae Kim Date: Thu, 17 May 2018 12:28:37 -0400 Message-ID: Subject: KASAN: use-after-free Write in do_con_write To: gregkh@linuxfoundation.org, jslaby@suse.com Cc: Byoungyoung Lee , linux-kernel@vger.kernel.org, DaeRyong Jeong Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We report the crash: "KASAN: use-after-free Write in do_con_write" This crash was found in v4.17-rc3. Specifically, memory access (write operation) is invalid, and it is detected by KASAN. C repro code: https://kiwi.cs.purdue.edu/static/alexkkid-fuzzer/repro-c4a1f8.c kernel config: https://kiwi.cs.purdue.edu/static/alexkkid-fuzzer/kernel-config-v4.17-rc3 Crash log: ============================================================== BUG: KASAN: use-after-free in do_con_write.part.20+0x1a14/0x1b70 drivers/tty/vt/vt.c:2397 Write of size 2 at addr ffff880000139042 by task getty/2803 CPU: 0 PID: 2803 Comm: getty Not tainted 4.17.0-rc3 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xc7/0x138 lib/dump_stack.c:113 print_address_description+0x6a/0x280 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x22f/0x350 mm/kasan/report.c:412 __asan_report_store2_noabort+0x17/0x20 mm/kasan/report.c:436 do_con_write.part.20+0x1a14/0x1b70 drivers/tty/vt/vt.c:2397 do_con_write drivers/tty/vt/vt.c:2790 [inline] con_write+0xb2/0xc0 drivers/tty/vt/vt.c:2786 n_tty_write+0x763/0xea0 drivers/tty/n_tty.c:2331 do_tty_write drivers/tty/tty_io.c:958 [inline] tty_write+0x48c/0x870 drivers/tty/tty_io.c:1042 __vfs_write+0x10d/0x610 fs/read_write.c:485 vfs_write+0x187/0x500 fs/read_write.c:549 ksys_write+0xd4/0x1a0 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0xa4/0x460 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7ffa6267ac00 RSP: 002b:00007ffee1ff7538 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000607340 RCX: 00007ffa6267ac00 RDX: 0000000000000002 RSI: 00000000004059fb RDI: 0000000000000001 RBP: 0000000000000002 R08: 000000000000000a R09: 00007ffa62944670 R10: 00007ffee1ff7620 R11: 0000000000000246 R12: 00007ffee1ff8090 R13: 00007ffa62d65690 R14: 00000000004059fb R15: 0000000000000000 The buggy address belongs to the page: page:ffffea0000004e40 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x0() raw: 0000000000000000 0000000000000000 0000000000000000 00000000ffffffff raw: ffffea0000004e60 ffffea0000004e60 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff880000138f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff880000138f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff880000139000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff880000139080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff880000139100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ============================================================== Thanks, Kyungtae Kim