Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754647AbeANANg (ORCPT + 1 other); Sat, 13 Jan 2018 19:13:36 -0500 Received: from www62.your-server.de ([213.133.104.62]:42540 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751168AbeANANe (ORCPT ); Sat, 13 Jan 2018 19:13:34 -0500 Subject: Re: KASAN: slab-out-of-bounds Read in map_lookup_elem To: syzbot , ast@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <001a11445a8803c8c705629eb602@google.com> From: Daniel Borkmann Message-ID: <461fe119-d452-6270-7126-46dd208a2767@iogearbox.net> Date: Sun, 14 Jan 2018 01:13:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <001a11445a8803c8c705629eb602@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 01/13/2018 02:58 AM, syzbot wrote: > Hello, > > syzkaller hit the following crash on 19d28fbd306e7ae7c1acf05c3e6968b56f0d196b > git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.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 Fixed here as well: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=bbeb6e4323dad9b5e0ee9f60c223dd532e2403b1 > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+e631b5eb810eae08510d@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. > > audit: type=1400 audit(1515782899.456:8): avc:  denied  { sys_admin } for  pid=3501 comm="syzkaller937663" capability=21  scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 > audit: type=1400 audit(1515782899.512:9): avc:  denied  { sys_chroot } for  pid=3502 comm="syzkaller937663" capability=18  scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 > ================================================================== > BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:344 [inline] > BUG: KASAN: slab-out-of-bounds in map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584 > Read of size 2097153 at addr ffff8801bfc7e690 by task syzkaller937663/3502 > > CPU: 0 PID: 3502 Comm: syzkaller937663 Not tainted 4.15.0-rc7+ #185 > 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:252 >  kasan_report_error mm/kasan/report.c:351 [inline] >  kasan_report+0x25b/0x340 mm/kasan/report.c:409 >  check_memory_region_inline mm/kasan/kasan.c:260 [inline] >  check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 >  memcpy+0x23/0x50 mm/kasan/kasan.c:302 >  memcpy include/linux/string.h:344 [inline] >  map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584 >  SYSC_bpf kernel/bpf/syscall.c:1808 [inline] >  SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1782 >  entry_SYSCALL_64_fastpath+0x23/0x9a > RIP: 0033:0x440ab9 > RSP: 002b:00000000007dff68 EFLAGS: 00000203 ORIG_RAX: 0000000000000141 > RAX: ffffffffffffffda RBX: 00007fffc494ea60 RCX: 0000000000440ab9 > RDX: 0000000000000018 RSI: 0000000020eab000 RDI: 0000000000000001 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000203 R12: 0000000000402290 > R13: 0000000000402320 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 3502: >  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 >  __do_kmalloc_node mm/slab.c:3672 [inline] >  __kmalloc_node+0x47/0x70 mm/slab.c:3679 >  kmalloc_node include/linux/slab.h:541 [inline] >  bpf_map_area_alloc+0x32/0x80 kernel/bpf/syscall.c:123 >  array_map_alloc+0x351/0xa00 kernel/bpf/arraymap.c:96 >  find_and_alloc_map kernel/bpf/syscall.c:105 [inline] >  map_create kernel/bpf/syscall.c:404 [inline] >  SYSC_bpf kernel/bpf/syscall.c:1805 [inline] >  SyS_bpf+0x7f8/0x4400 kernel/bpf/syscall.c:1782 >  entry_SYSCALL_64_fastpath+0x23/0x9a > > Freed by task 1966: >  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:3488 [inline] >  kfree+0xd6/0x260 mm/slab.c:3803 >  seq_release fs/seq_file.c:366 [inline] >  single_release+0x80/0xb0 fs/seq_file.c:602 >  __fput+0x327/0x7e0 fs/file_table.c:210 >  ____fput+0x15/0x20 fs/file_table.c:244 >  task_work_run+0x199/0x270 kernel/task_work.c:113 >  tracehook_notify_resume include/linux/tracehook.h:191 [inline] >  exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 >  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+0x98/0x9a > > The buggy address belongs to the object at ffff8801bfc7e5c0 >  which belongs to the cache kmalloc-256 of size 256 > The buggy address is located 208 bytes inside of >  256-byte region [ffff8801bfc7e5c0, ffff8801bfc7e6c0) > The buggy address belongs to the page: > page:ffffea0006ff1f80 count:1 mapcount:0 mapping:ffff8801bfc7e0c0 index:0x0 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffff8801bfc7e0c0 0000000000000000 000000010000000c > raw: ffffea00070149e0 ffffea0006ff2be0 ffff8801dac007c0 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: >  ffff8801bfc7e580: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 >  ffff8801bfc7e600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffff8801bfc7e680: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc >                                            ^ >  ffff8801bfc7e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >  ffff8801bfc7e780: 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.