Message-ID: <CAKFNMo=2NxnBy-zfMwMCerVSoFpErX_JNnEUJeiqp6SrN7grcQ@mail.gmail.com>
Date:   Tue, 18 Oct 2022 08:26:30 +0900
From:   Ryusuke Konishi <konishi.ryusuke@...il.com>
To:     syzbot <syzbot+e7b15dcc1051f8b99e58@...kaller.appspotmail.com>
Cc:     linux-kernel@...r.kernel.org, linux-nilfs@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] KASAN: use-after-free Read in nilfs_iget

On Tue, Oct 18, 2022 at 6:57 AM syzbot wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    493ffd6605b2 Merge tag 'ucount-rlimits-cleanups-for-v5.19'..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1368e0aa880000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d19f5d16783f901
> dashboard link: https://syzkaller.appspot.com/bug?extid=e7b15dcc1051f8b99e58
> compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f1ff6481e26f/disk-493ffd66.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/101bd3c7ae47/vmlinux-493ffd66.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e7b15dcc1051f8b99e58@...kaller.appspotmail.com
>
> loop5: detected capacity change from 0 to 2048
> ==================================================================
> BUG: KASAN: use-after-free in __nilfs_read_inode fs/nilfs2/inode.c:477 [inline]
> BUG: KASAN: use-after-free in nilfs_iget+0x242/0x8b0 fs/nilfs2/inode.c:603
> Read of size 8 at addr ffff8880201cba30 by task syz-executor.5/22617
>
> CPU: 1 PID: 22617 Comm: syz-executor.5 Not tainted 6.0.0-syzkaller-09423-g493ffd6605b2 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
>  print_address_description+0x65/0x4b0 mm/kasan/report.c:317
>  print_report+0x108/0x1f0 mm/kasan/report.c:433
>  kasan_report+0xc3/0xf0 mm/kasan/report.c:495
>  __nilfs_read_inode fs/nilfs2/inode.c:477 [inline]
>  nilfs_iget+0x242/0x8b0 fs/nilfs2/inode.c:603
>  nilfs_lookup+0xca/0x110 fs/nilfs2/namei.c:63
>  lookup_open fs/namei.c:3391 [inline]
>  open_last_lookups fs/namei.c:3481 [inline]
>  path_openat+0x10e6/0x2df0 fs/namei.c:3688
>  do_filp_open+0x264/0x4f0 fs/namei.c:3718
>  do_sys_openat2+0x124/0x4e0 fs/open.c:1310
>  do_sys_open fs/open.c:1326 [inline]
>  __do_sys_openat fs/open.c:1342 [inline]
>  __se_sys_openat fs/open.c:1337 [inline]
>  __x64_sys_openat+0x243/0x290 fs/open.c:1337
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f7bb388b5a9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f7bb4a20168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007f7bb39abf80 RCX: 00007f7bb388b5a9
> RDX: 0000000000010000 RSI: 0000000020000080 RDI: ffffffffffffff9c
> RBP: 00007f7bb38e6580 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000082 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffc185e581f R14: 00007f7bb4a20300 R15: 0000000000022000
>  </TASK>
>
> Allocated by task 22617:
>  kasan_save_stack mm/kasan/common.c:38 [inline]
>  kasan_set_track mm/kasan/common.c:45 [inline]
>  set_alloc_info mm/kasan/common.c:437 [inline]
>  ____kasan_kmalloc+0xcd/0x100 mm/kasan/common.c:516
>  kasan_kmalloc include/linux/kasan.h:234 [inline]
>  kmem_cache_alloc_trace+0x97/0x310 mm/slub.c:3289
>  kmalloc include/linux/slab.h:600 [inline]
>  kzalloc include/linux/slab.h:733 [inline]
>  nilfs_find_or_create_root+0x142/0x4f0 fs/nilfs2/the_nilfs.c:747
>  nilfs_attach_checkpoint+0xcd/0x4a0 fs/nilfs2/super.c:519
>  nilfs_fill_super+0x2e8/0x5d0 fs/nilfs2/super.c:1064
>  nilfs_mount+0x613/0x9b0 fs/nilfs2/super.c:1317
>  legacy_get_tree+0xea/0x180 fs/fs_context.c:610
>  vfs_get_tree+0x88/0x270 fs/super.c:1530
>  do_new_mount+0x289/0xad0 fs/namespace.c:3040
>  do_mount fs/namespace.c:3383 [inline]
>  __do_sys_mount fs/namespace.c:3591 [inline]
>  __se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3568
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> Freed by task 22617:
>  kasan_save_stack mm/kasan/common.c:38 [inline]
>  kasan_set_track+0x3d/0x60 mm/kasan/common.c:45
>  kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370
>  ____kasan_slab_free+0xd8/0x120 mm/kasan/common.c:367
>  kasan_slab_free include/linux/kasan.h:200 [inline]
>  slab_free_hook mm/slub.c:1759 [inline]
>  slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1785
>  slab_free mm/slub.c:3539 [inline]
>  kfree+0xda/0x210 mm/slub.c:4567
>  nilfs_evict_inode+0x253/0x3d0 fs/nilfs2/inode.c:924
>  evict+0x2a4/0x620 fs/inode.c:664
>  nilfs_new_inode+0x6b8/0x8a0
>  nilfs_create+0xdc/0x2d0 fs/nilfs2/namei.c:85
>  lookup_open fs/namei.c:3413 [inline]
>  open_last_lookups fs/namei.c:3481 [inline]
>  path_openat+0x12d0/0x2df0 fs/namei.c:3688
>  do_filp_open+0x264/0x4f0 fs/namei.c:3718
>  do_sys_openat2+0x124/0x4e0 fs/open.c:1310
>  do_sys_open fs/open.c:1326 [inline]
>  __do_sys_creat fs/open.c:1402 [inline]
>  __se_sys_creat fs/open.c:1396 [inline]
>  __x64_sys_creat+0x11f/0x160 fs/open.c:1396
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> Last potentially related work creation:
>  kasan_save_stack+0x2b/0x50 mm/kasan/common.c:38
>  __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:348
>  kvfree_call_rcu+0x112/0x880 kernel/rcu/tree.c:3341
>  drop_sysctl_table+0x307/0x480 fs/proc/proc_sysctl.c:1716
>  drop_sysctl_table+0x319/0x480 fs/proc/proc_sysctl.c:1719
>  unregister_sysctl_table+0x87/0x140 fs/proc/proc_sysctl.c:1754
>  neigh_sysctl_unregister+0x74/0x90 net/core/neighbour.c:3871
>  devinet_sysctl_unregister net/ipv4/devinet.c:2638 [inline]
>  inetdev_event+0xe25/0x14a0 net/ipv4/devinet.c:1610
>  notifier_call_chain kernel/notifier.c:87 [inline]
>  raw_notifier_call_chain+0xe7/0x170 kernel/notifier.c:455
>  call_netdevice_notifiers_info net/core/dev.c:1945 [inline]
>  call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
>  call_netdevice_notifiers net/core/dev.c:1997 [inline]
>  dev_change_name+0x695/0x990 net/core/dev.c:1226
>  do_setlink+0xa73/0x3d40 net/core/rtnetlink.c:2761
>  __rtnl_newlink net/core/rtnetlink.c:3547 [inline]
>  rtnl_newlink+0x1748/0x1fa0 net/core/rtnetlink.c:3594
>  rtnetlink_rcv_msg+0x772/0xe60 net/core/rtnetlink.c:6091
>  netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2540
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x7e7/0x9c0 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x9b3/0xcd0 net/netlink/af_netlink.c:1921
>  sock_sendmsg_nosec net/socket.c:714 [inline]
>  sock_sendmsg net/socket.c:734 [inline]
>  __sys_sendto+0x46e/0x5f0 net/socket.c:2117
>  __do_sys_sendto net/socket.c:2129 [inline]
>  __se_sys_sendto net/socket.c:2125 [inline]
>  __x64_sys_sendto+0xda/0xf0 net/socket.c:2125
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> The buggy address belongs to the object at ffff8880201cba00
>  which belongs to the cache kmalloc-256 of size 256
> The buggy address is located 48 bytes inside of
>  256-byte region [ffff8880201cba00, ffff8880201cbb00)
>
> The buggy address belongs to the physical page:
> page:ffffea0000807280 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x201ca
> head:ffffea0000807280 order:1 compound_mapcount:0 compound_pincount:0
> flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
> raw: 00fff00000010200 ffffea00011eb480 dead000000000005 ffff888012041b40
> raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3644, tgid 3644 (syz-executor.5), ts 137885168909, free_ts 135490844091
>  prep_new_page mm/page_alloc.c:2532 [inline]
>  get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4283
>  __alloc_pages+0x259/0x560 mm/page_alloc.c:5549
>  alloc_slab_page+0x70/0xf0 mm/slub.c:1829
>  allocate_slab+0x5e/0x520 mm/slub.c:1974
>  new_slab mm/slub.c:2034 [inline]
>  ___slab_alloc+0x3ee/0xc40 mm/slub.c:3036
>  __slab_alloc mm/slub.c:3123 [inline]
>  slab_alloc_node mm/slub.c:3214 [inline]
>  slab_alloc mm/slub.c:3256 [inline]
>  __kmalloc+0x2bd/0x370 mm/slub.c:4425
>  kmalloc include/linux/slab.h:605 [inline]
>  kzalloc include/linux/slab.h:733 [inline]
>  new_dir fs/proc/proc_sysctl.c:978 [inline]
>  get_subdir fs/proc/proc_sysctl.c:1022 [inline]
>  __register_sysctl_table+0xb63/0x11e0 fs/proc/proc_sysctl.c:1373
>  __addrconf_sysctl_register+0x25e/0x3b0 net/ipv6/addrconf.c:7083
>  addrconf_sysctl_register+0x128/0x180 net/ipv6/addrconf.c:7130
>  ipv6_add_dev+0xc44/0x1200 net/ipv6/addrconf.c:450
>  ipv6_find_idev+0xa3/0x1b0 net/ipv6/addrconf.c:488
>  inet6_rtm_newaddr+0x634/0x2080 net/ipv6/addrconf.c:4908
>  rtnetlink_rcv_msg+0x772/0xe60 net/core/rtnetlink.c:6091
>  netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2540
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x7e7/0x9c0 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x9b3/0xcd0 net/netlink/af_netlink.c:1921
> page last free stack trace:
>  reset_page_owner include/linux/page_owner.h:24 [inline]
>  free_pages_prepare mm/page_alloc.c:1449 [inline]
>  free_pcp_prepare+0x812/0x900 mm/page_alloc.c:1499
>  free_unref_page_prepare mm/page_alloc.c:3380 [inline]
>  free_unref_page+0x7d/0x5f0 mm/page_alloc.c:3476
>  free_slab mm/slub.c:2073 [inline]
>  discard_slab mm/slub.c:2079 [inline]
>  __unfreeze_partials+0x1ab/0x200 mm/slub.c:2553
>  put_cpu_partial+0x106/0x170 mm/slub.c:2629
>  qlist_free_all+0x2b/0x70 mm/kasan/quarantine.c:187
>  kasan_quarantine_reduce+0x169/0x180 mm/kasan/quarantine.c:294
>  __kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:447
>  kasan_slab_alloc include/linux/kasan.h:224 [inline]
>  slab_post_alloc_hook mm/slab.h:727 [inline]
>  slab_alloc_node mm/slub.c:3248 [inline]
>  slab_alloc mm/slub.c:3256 [inline]
>  kmem_cache_alloc_trace+0x1de/0x310 mm/slub.c:3287
>  kmalloc include/linux/slab.h:600 [inline]
>  kzalloc include/linux/slab.h:733 [inline]
>  tomoyo_dump_page+0xdb/0x440 security/tomoyo/domain.c:906
>  tomoyo_scan_bprm security/tomoyo/condition.c:130 [inline]
>  tomoyo_condition+0x1cd8/0x2b70 security/tomoyo/condition.c:1120
>  tomoyo_check_acl+0x17a/0x410 security/tomoyo/domain.c:177
>  tomoyo_execute_permission+0x134/0x410 security/tomoyo/file.c:615
>  tomoyo_find_next_domain+0x41a/0x1d80 security/tomoyo/domain.c:752
>  tomoyo_bprm_check_security+0xe3/0x130 security/tomoyo/tomoyo.c:101
>  security_bprm_check+0x50/0xb0 security/security.c:869
>  search_binary_handler fs/exec.c:1713 [inline]
>  exec_binprm fs/exec.c:1766 [inline]
>  bprm_execve+0x817/0x1590 fs/exec.c:1835
>
> Memory state around the buggy address:
>  ffff8880201cb900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff8880201cb980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffff8880201cba00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                      ^
>  ffff8880201cba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8880201cbb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

Looks like the same UAF bug as below according to the stack trace:

#syz dup: KASAN: use-after-free Read in nilfs_segctor_confirm

The bugfix for this is the patch titled "nilfs2: fix use-after-free
bug of struct nilfs_root", which was merged in the mainline after the
tested commit.

Ryusuke Konishi

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