Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751659AbbKZNfR (ORCPT ); Thu, 26 Nov 2015 08:35:17 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:35109 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751038AbbKZNfO (ORCPT ); Thu, 26 Nov 2015 08:35:14 -0500 MIME-Version: 1.0 From: Dmitry Vyukov Date: Thu, 26 Nov 2015 14:34:53 +0100 Message-ID: Subject: use-after-free in n_tty_read To: Greg Kroah-Hartman , Jiri Slaby , LKML Cc: Kostya Serebryany , Alexander Potapenko , Eric Dumazet , Sasha Levin , Peter Hurley 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: 5171 Lines: 97 Hello, I've hit the following report once after booting a VM and then scp a file into it. It is not reproducible. But maybe the stacks will give you some hint as to how it could happen: ================================================================== BUG: KASAN: use-after-free in n_tty_read+0x1d53/0x1e60 at addr ffff880061ec3ae0 Read of size 8 by task sshd/5796 ============================================================================= BUG kmalloc-16 (Not tainted): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in tty_ldisc_get.part.3+0x61/0x130 age=11 cpu=3 pid=5796 [< none >] ___slab_alloc+0x489/0x4e0 mm/slub.c:2438 [< none >] __slab_alloc+0x4c/0x90 mm/slub.c:2467 [< inline >] slab_alloc_node mm/slub.c:2530 [< inline >] slab_alloc mm/slub.c:2572 [< none >] kmem_cache_alloc_trace+0x1c6/0x210 mm/slub.c:2589 [< inline >] kmalloc include/linux/slab.h:458 [< none >] tty_ldisc_get.part.3+0x61/0x130 drivers/tty/tty_ldisc.c:171 [< inline >] tty_ldisc_get drivers/tty/tty_ldisc.c:801 [< none >] tty_ldisc_init+0x13/0x70 drivers/tty/tty_ldisc.c:802 [< none >] alloc_tty_struct+0x103/0x810 drivers/tty/tty_io.c:3115 [< none >] pty_common_install+0x1a2/0x940 drivers/tty/pty.c:399 [< none >] pty_unix98_install+0xb/0x10 drivers/tty/pty.c:674 [< inline >] tty_driver_install_tty drivers/tty/tty_io.c:1430 [< none >] tty_init_dev+0xdb/0x3e0 drivers/tty/tty_io.c:1529 [< none >] ptmx_open+0xbc/0x2c0 drivers/tty/pty.c:762 [< none >] chrdev_open+0x1ef/0x570 fs/char_dev.c:388 [< none >] do_dentry_open+0x5d2/0xab0 fs/open.c:736 [< none >] vfs_open+0x166/0x1e0 fs/open.c:853 [< inline >] do_last fs/namei.c:3192 [< none >] path_openat+0xa5c/0x5e00 fs/namei.c:3324 [< none >] do_filp_open+0x170/0x230 fs/namei.c:3359 [< none >] do_sys_open+0x180/0x360 fs/open.c:1025 INFO: Freed in tty_ldisc_reinit+0xc8/0x1b0 age=7 cpu=0 pid=5798 [< none >] __slab_free+0x206/0x360 mm/slub.c:2648 (discriminator 1) [< inline >] slab_free mm/slub.c:2803 [< none >] kfree+0x1a2/0x1c0 mm/slub.c:3632 [< inline >] tty_ldisc_put drivers/tty/tty_ldisc.c:194 [< none >] tty_ldisc_reinit+0xc8/0x1b0 drivers/tty/tty_ldisc.c:635 [< none >] tty_ldisc_hangup+0x1fa/0x5f0 drivers/tty/tty_ldisc.c:708 [< none >] __tty_hangup+0x423/0xad0 drivers/tty/tty_io.c:729 [< inline >] tty_vhangup drivers/tty/tty_io.c:802 [< none >] tty_vhangup_self+0x1c/0x40 drivers/tty/tty_io.c:820 [< none >] sys_vhangup+0x1e/0x30 fs/open.c:1121 [< none >] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 INFO: Slab 0xffffea000187b080 objects=23 used=16 fp=0xffff880061ec3ae0 flags=0x5fffc0000004080 INFO: Object 0xffff880061ec3ae0 @offset=6880 fp=0xffff880061ec3580 Bytes b4 ffff880061ec3ad0: f1 c1 fb ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ Object ffff880061ec3ae0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk. Redzone ffff880061ec3af0: bb bb bb bb bb bb bb bb ........ Padding ffff880061ec3c30: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ CPU: 3 PID: 5796 Comm: sshd Tainted: G B 4.4.0-rc2+ #51 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffff880061ec2000 ffff88006a377928 ffffffff826c8be0 ffff88003e807980 ffff88006a377958 ffffffff815f1604 ffff88003e807980 ffffea000187b080 ffff880061ec3ae0 ffff8800620c4670 ffff88006a377980 ffffffff815f775f Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [] dump_stack+0x44/0x64 lib/dump_stack.c:50 [] print_trailer+0xf4/0x150 mm/slub.c:652 [] object_err+0x2f/0x40 mm/slub.c:659 [< inline >] print_address_description mm/kasan/report.c:138 [] kasan_report_error+0x210/0x520 mm/kasan/report.c:236 [< inline >] kasan_report mm/kasan/report.c:259 [] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:280 [< inline >] n_tty_check_unthrottle drivers/tty/n_tty.c:262 [] n_tty_read+0x1d53/0x1e60 drivers/tty/n_tty.c:2302 [] tty_read+0x146/0x230 drivers/tty/tty_io.c:1071 [] __vfs_read+0xdb/0x490 fs/read_write.c:432 [] vfs_read+0xdb/0x2d0 fs/read_write.c:454 [< inline >] SYSC_read fs/read_write.c:569 [] SyS_read+0x10c/0x220 fs/read_write.c:562 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 ================================================================== On commit 6ffeba9607343f15303a399bc402a538800d89d9. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/