KASAN: A slab-use-after-free Read bug in btrfs_search_slot in fs/btrfs/ctree.c

[butt3rflyh4ck]

Hi, there is a slab-use-after-free Read bug in btrfs_search_slot in
fs/btrfs/ctree.c, I reproduce it in the latest kernel too.

#simple analysis
When a thread calls BTRFS_QUOTA_CTL_ENABLE to create a new quota tree
and then calls BTRFS_QUOTA_CTL_DISABLE to release a quota tree, there
is a race condition window in between. During this time, if another
thread calls BTRFS_IOC_QGROUP_ASSIGN to update the status and
information of the dirty qgroup, it would call update_qgroup_info_item
to update, it may trigger a use-after-free (UAF) vulnerability.

#crash log
[74672.719605][T27736]
==================================================================
[74672.720403][T27736] BUG: KASAN: slab-use-after-free in
btrfs_search_slot+0x2962/0x2db0
[74672.721113][T27736] Read of size 8 at addr ffff888022ec0208 by task
btrfs_search_sl/27736
[74672.721794][T27736]
[74672.721995][T27736] CPU: 1 PID: 27736 Comm: btrfs_search_sl Not
tainted 6.3.0-rc3 #37
[74672.722653][T27736] Hardware name: QEMU Standard PC (i440FX + PIIX,
1996), BIOS 1.15.0-1 04/01/2014
[74672.723377][T27736] Call Trace:
[74672.723688][T27736]  <TASK>
[74672.723968][T27736]  dump_stack_lvl+0xd9/0x150
[74672.724405][T27736]  print_report+0xc1/0x5e0
[74672.724810][T27736]  ? __virt_addr_valid+0x61/0x2e0
[74672.725247][T27736]  ? __phys_addr+0xc9/0x150
[74672.725635][T27736]  ? btrfs_search_slot+0x2962/0x2db0
[74672.726092][T27736]  kasan_report+0xc0/0xf0
[74672.726469][T27736]  ? btrfs_search_slot+0x2962/0x2db0
[74672.726934][T27736]  btrfs_search_slot+0x2962/0x2db0
[74672.727373][T27736]  ? fs_reclaim_acquire+0xba/0x160
[74672.727802][T27736]  ? split_leaf+0x13d0/0x13d0
[74672.728236][T27736]  ? rcu_is_watching+0x12/0xb0
[74672.728673][T27736]  ? kmem_cache_alloc+0x338/0x3c0
[74672.729132][T27736]  update_qgroup_status_item+0xf7/0x320
[74672.729614][T27736]  ? add_qgroup_rb+0x3d0/0x3d0
[74672.730019][T27736]  ? do_raw_spin_lock+0x12d/0x2b0
[74672.730470][T27736]  ? spin_bug+0x1d0/0x1d0
[74672.730847][T27736]  btrfs_run_qgroups+0x5de/0x840
[74672.731290][T27736]  ? btrfs_qgroup_rescan_worker+0xa70/0xa70
[74672.731788][T27736]  ? __del_qgroup_relation+0x4ba/0xe00
[74672.732288][T27736]  btrfs_ioctl+0x3d58/0x5d80
[74672.732705][T27736]  ? tomoyo_path_number_perm+0x16a/0x550
[74672.733217][T27736]  ? tomoyo_execute_permission+0x4a0/0x4a0
[74672.733701][T27736]  ? btrfs_ioctl_get_supported_features+0x50/0x50
[74672.734237][T27736]  ? __sanitizer_cov_trace_switch+0x54/0x90
[74672.734754][T27736]  ? do_vfs_ioctl+0x132/0x1660
[74672.735170][T27736]  ? vfs_fileattr_set+0xc40/0xc40
[74672.735610][T27736]  ? _raw_spin_unlock_irq+0x2e/0x50
[74672.736092][T27736]  ? sigprocmask+0xf2/0x340
[74672.736497][T27736]  ? __fget_files+0x26a/0x480
[74672.736932][T27736]  ? bpf_lsm_file_ioctl+0x9/0x10
[74672.737368][T27736]  ? btrfs_ioctl_get_supported_features+0x50/0x50
[74672.737936][T27736]  __x64_sys_ioctl+0x198/0x210
[74672.738356][T27736]  do_syscall_64+0x39/0xb0
[74672.738751][T27736]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[74672.739289][T27736] RIP: 0033:0x4556ad
[74672.739634][T27736] Code: c3 e8 c7 1f 00 00 0f 1f 80 00 00 00 00 f3
0f 1e fa 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 f8
[74672.741232][T27736] RSP: 002b:00007fa5f496b178 EFLAGS: 00000283
ORIG_RAX: 0000000000000010
[74672.741930][T27736] RAX: ffffffffffffffda RBX: 00007fa5f496b640
RCX: 00000000004556ad
[74672.742601][T27736] RDX: 0000000020000000 RSI: 0000000040189429
RDI: 0000000000000003
[74672.743245][T27736] RBP: 00007fa5f496b1a0 R08: 0000000000000000
R09: 0000000000000000
[74672.743919][T27736] R10: 0000000000000000 R11: 0000000000000283
R12: 00007fa5f496b640
[74672.744622][T27736] R13: 000000000000006e R14: 0000000000417b20
R15: 00007fa5f494b000
[74672.745272][T27736]  </TASK>
[74672.745533][T27736]
[74672.745778][T27736] Allocated by task 27677:
[74672.746163][T27736]  kasan_save_stack+0x22/0x40
[74672.746571][T27736]  kasan_set_track+0x25/0x30
[74672.746981][T27736]  __kasan_kmalloc+0xa4/0xb0
[74672.747439][T27736]  btrfs_alloc_root+0x48/0x90
[74672.747856][T27736]  btrfs_create_tree+0x146/0xa20
[74672.748294][T27736]  btrfs_quota_enable+0x461/0x1d20
[74672.748683][T27736]  btrfs_ioctl+0x4a1c/0x5d80
[74672.749057][T27736]  __x64_sys_ioctl+0x198/0x210
[74672.749429][T27736]  do_syscall_64+0x39/0xb0
[74672.749774][T27736]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[74672.750646][T27736]
[74672.750937][T27736] Freed by task 27677:
[74672.751699][T27736]  kasan_save_stack+0x22/0x40
[74672.752479][T27736]  kasan_set_track+0x25/0x30
[74672.753236][T27736]  kasan_save_free_info+0x2e/0x50
[74672.754041][T27736]  ____kasan_slab_free+0x162/0x1c0
[74672.754948][T27736]  slab_free_freelist_hook+0x89/0x1c0
[74672.755822][T27736]  __kmem_cache_free+0xaf/0x2e0
[74672.756642][T27736]  btrfs_put_root+0x1ff/0x2b0
[74672.757379][T27736]  btrfs_quota_disable+0x80a/0xbc0
[74672.758262][T27736]  btrfs_ioctl+0x3e5f/0x5d80
[74672.758996][T27736]  __x64_sys_ioctl+0x198/0x210
[74672.759843][T27736]  do_syscall_64+0x39/0xb0
[74672.760685][T27736]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[74672.761639][T27736]
[74672.762018][T27736] The buggy address belongs to the object at
ffff888022ec0000
[74672.762018][T27736]  which belongs to the cache kmalloc-4k of size 4096
[74672.764569][T27736] The buggy address is located 520 bytes inside of
[74672.764569][T27736]  freed 4096-byte region [ffff888022ec0000,
ffff888022ec1000)
[74672.766900][T27736]
[74672.767254][T27736] The buggy address belongs to the physical page:
[74672.768271][T27736] page:ffffea00008bb000 refcount:1 mapcount:0
mapping:0000000000000000 index:0x0 pfn:0x22ec0
[74672.769366][T27736] head:ffffea00008bb000 order:3 entire_mapcount:0
nr_pages_mapped:0 pincount:0
[74672.770239][T27736] flags:
0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
[74672.771510][T27736] raw: 00fff00000010200 ffff888012842140
ffffea000054ba00 dead000000000002
[74672.772770][T27736] raw: 0000000000000000 0000000000040004
00000001ffffffff 0000000000000000
[74672.773941][T27736] page dumped because: kasan: bad access detected
[74672.774788][T27736] page_owner tracks the page as allocated
[74672.775407][T27736] page last allocated via order 3, migratetype
Unmovable, gfp_mask
0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
pid 88
[74672.777249][T27736]  get_page_from_freelist+0x119c/0x2d50
[74672.777719][T27736]  __alloc_pages+0x1cb/0x4a0
[74672.778106][T27736]  alloc_pages+0x1aa/0x270
[74672.778493][T27736]  allocate_slab+0x260/0x390
[74672.778901][T27736]  ___slab_alloc+0xa9a/0x13e0
[74672.779308][T27736]  __slab_alloc.constprop.0+0x56/0xb0
[74672.779771][T27736]  __kmem_cache_alloc_node+0x136/0x320
[74672.780479][T27736]  __kmalloc+0x4e/0x1a0
[74672.781123][T27736]  tomoyo_realpath_from_path+0xc3/0x600
[74672.782021][T27736]  tomoyo_path_perm+0x22f/0x420
[74672.782862][T27736]  tomoyo_path_unlink+0x92/0xd0
[74672.783780][T27736]  security_path_unlink+0xdb/0x150
[74672.784648][T27736]  do_unlinkat+0x377/0x680
[74672.785278][T27736]  __x64_sys_unlink+0xca/0x110
[74672.785959][T27736]  do_syscall_64+0x39/0xb0
[74672.786623][T27736]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[74672.787544][T27736] page last free stack trace:
[74672.788247][T27736]  free_pcp_prepare+0x4e5/0x920
[74672.789067][T27736]  free_unref_page+0x1d/0x4e0
[74672.789854][T27736]  __unfreeze_partials+0x17c/0x1a0
[74672.790707][T27736]  qlist_free_all+0x6a/0x180
[74672.791406][T27736]  kasan_quarantine_reduce+0x189/0x1d0
[74672.792277][T27736]  __kasan_slab_alloc+0x64/0x90
[74672.793033][T27736]  kmem_cache_alloc+0x17c/0x3c0
[74672.793789][T27736]  getname_flags.part.0+0x50/0x4e0
[74672.794559][T27736]  getname_flags+0x9e/0xe0
[74672.795202][T27736]  vfs_fstatat+0x77/0xb0
[74672.795861][T27736]  __do_sys_newlstat+0x84/0x100
[74672.796638][T27736]  do_syscall_64+0x39/0xb0
[74672.797276][T27736]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[74672.798060][T27736]
[74672.798411][T27736] Memory state around the buggy address:
[74672.799239][T27736]  ffff888022ec0100: fb fb fb fb fb fb fb fb fb
fb fb fb fb fb fb fb
[74672.800425][T27736]  ffff888022ec0180: fb fb fb fb fb fb fb fb fb
fb fb fb fb fb fb fb
[74672.801562][T27736] >ffff888022ec0200: fb fb fb fb fb fb fb fb fb
fb fb fb fb fb fb fb
[74672.802809][T27736]                       ^
[74672.803509][T27736]  ffff888022ec0280: fb fb fb fb fb fb fb fb fb
fb fb fb fb fb fb fb
[74672.804419][T27736]  ffff888022ec0300: fb fb fb fb fb fb fb fb fb
fb fb fb fb fb fb fb
[74672.805112][T27736]
==================================================================


Regards,
 butt3rflyh4ck.

-- 
Active Defense Lab of Venustech