Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751959AbeADFN3 (ORCPT + 1 other); Thu, 4 Jan 2018 00:13:29 -0500 Received: from mail-wm0-f50.google.com ([74.125.82.50]:47049 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750746AbeADFN2 (ORCPT ); Thu, 4 Jan 2018 00:13:28 -0500 X-Google-Smtp-Source: ACJfBotq1/UGOzXM+NcyaxEDkj71N8lvwW+ZubBpr4pjvL7eKEkFeDCh8R+SwB10OyCimhfHHzLtX3eCYEr6cMKV2fM= MIME-Version: 1.0 In-Reply-To: <94eb2c0ce3aa27cfa40561ec2dc3@google.com> References: <94eb2c0ce3aa27cfa40561ec2dc3@google.com> From: Eric Dumazet Date: Wed, 3 Jan 2018 21:13:25 -0800 Message-ID: Subject: Re: KASAN: use-after-free Read in __dev_queue_xmit To: syzbot Cc: alexander.deucher@amd.com, Andrey Konovalov , Anoob Soman , chris@chris-wilson.co.uk, David Miller , elena.reshetova@intel.com, Greg Kroah-Hartman , Kees Cook , LKML , Mike Maloney , mchehab@kernel.org, netdev , rami.rosen@intel.com, Sowmini Varadhan , syzkaller-bugs@googlegroups.com, Willem de Bruijn Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Wed, Jan 3, 2018 at 8:58 PM, syzbot wrote: > Hello, > > syzkaller hit the following crash on > 37759fa6d0fa9e4d6036d19ac12f555bfc0aeafd > git://git.cmpxchg.org/linux-mmots.git/master > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached > Raw console output is attached. > C reproducer is attached > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > for information about syzkaller reproducers > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+71d74a5406d02057d559@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > ================================================================== > BUG: KASAN: use-after-free in __tcp_hdrlen include/linux/tcp.h:35 [inline] > BUG: KASAN: use-after-free in tcp_hdrlen include/linux/tcp.h:40 [inline] > BUG: KASAN: use-after-free in qdisc_pkt_len_init net/core/dev.c:3160 > [inline] > BUG: KASAN: use-after-free in __dev_queue_xmit+0x20d3/0x2200 > net/core/dev.c:3465 > Read of size 2 at addr ffff8801cb360d38 by task syzkaller769484/3147 > > CPU: 0 PID: 3147 Comm: syzkaller769484 Not tainted 4.15.0-rc4-mm1+ #49 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > print_address_description+0x73/0x250 mm/kasan/report.c:256 > kasan_report_error mm/kasan/report.c:355 [inline] > kasan_report+0x23b/0x360 mm/kasan/report.c:413 > __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:432 > __tcp_hdrlen include/linux/tcp.h:35 [inline] > tcp_hdrlen include/linux/tcp.h:40 [inline] > qdisc_pkt_len_init net/core/dev.c:3160 [inline] > __dev_queue_xmit+0x20d3/0x2200 net/core/dev.c:3465 > dev_queue_xmit+0x17/0x20 net/core/dev.c:3554 > packet_snd net/packet/af_packet.c:2943 [inline] > packet_sendmsg+0x3ad5/0x60a0 net/packet/af_packet.c:2968 > sock_sendmsg_nosec net/socket.c:628 [inline] > sock_sendmsg+0xca/0x110 net/socket.c:638 > sock_write_iter+0x31a/0x5d0 net/socket.c:907 > call_write_iter include/linux/fs.h:1776 [inline] > new_sync_write fs/read_write.c:469 [inline] > __vfs_write+0x684/0x970 fs/read_write.c:482 > vfs_write+0x189/0x510 fs/read_write.c:544 > SYSC_write fs/read_write.c:589 [inline] > SyS_write+0xef/0x220 fs/read_write.c:581 > entry_SYSCALL_64_fastpath+0x1f/0x96 > RIP: 0033:0x444b89 > RSP: 002b:00000000007eff78 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 00007fff91d02bb0 RCX: 0000000000444b89 > RDX: 000000000000005d RSI: 0000000020384000 RDI: 0000000000000005 > RBP: 0000000000000000 R08: 0000000120080522 R09: 0000000120080522 > R10: 0000000120080522 R11: 0000000000000293 R12: 0000000000402780 > R13: 0000000000402810 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 1643: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 > kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3607 > kmalloc include/linux/slab.h:516 [inline] > kzalloc include/linux/slab.h:705 [inline] > kernfs_fop_open+0x357/0xeb0 fs/kernfs/file.c:648 > do_dentry_open+0x667/0xd40 fs/open.c:752 > vfs_open+0x107/0x220 fs/open.c:866 > do_last fs/namei.c:3397 [inline] > path_openat+0x1151/0x3530 fs/namei.c:3537 > do_filp_open+0x25b/0x3b0 fs/namei.c:3572 > do_sys_open+0x502/0x6d0 fs/open.c:1059 > SYSC_open fs/open.c:1077 [inline] > SyS_open+0x2d/0x40 fs/open.c:1072 > entry_SYSCALL_64_fastpath+0x1f/0x96 > > Freed by task 1643: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 > __cache_free mm/slab.c:3485 [inline] > kfree+0xd6/0x260 mm/slab.c:3800 > kernfs_fop_release+0x13f/0x180 fs/kernfs/file.c:783 > __fput+0x327/0x7e0 fs/file_table.c:209 > ____fput+0x15/0x20 fs/file_table.c:243 > task_work_run+0x199/0x270 kernel/task_work.c:113 > tracehook_notify_resume include/linux/tracehook.h:191 [inline] > exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:165 > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > entry_SYSCALL_64_fastpath+0x94/0x96 > > The buggy address belongs to the object at ffff8801cb360cc0 > which belongs to the cache kmalloc-512 of size 512 > The buggy address is located 120 bytes inside of > 512-byte region [ffff8801cb360cc0, ffff8801cb360ec0) > The buggy address belongs to the page: > page:ffffea00072cd800 count:1 mapcount:0 mapping:ffff8801cb360040 index:0x0 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffff8801cb360040 0000000000000000 0000000100000006 > raw: ffffea00072bb6a0 ffffea00072bf720 ffff8801dac00940 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801cb360c00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc > ffff8801cb360c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >> >> ffff8801cb360d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > ffff8801cb360d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801cb360e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is > merged > into any tree, please reply to this email with: > #syz fix: exact-commit-title > If you want to test a patch for this bug, please reply with: > #syz test: git://repo/address.git branch > and provide the patch inline or as an attachment. > To mark this as a duplicate of another syzbot report, please reply with: > #syz dup: exact-subject-of-another-report > If it's a one-off invalid bug report, please reply with: > #syz invalid > Note: if the crash happens again, it will cause creation of a new bug > report. > Note: all commands must start from beginning of the line in the email body. I guess skb_probe_transport_header() should be hardened to reject malicious packets given by user space, instead of being gentle.