queue-4.19/configfs-fix-possible-use-after-free-in-configfs_reg.patch

   1 From 5a9168e8fe444a960f0085e350c50222f3ad0daa Mon Sep 17 00:00:00 2001
   2 From: YueHaibing <yuehaibing@huawei.com>
   3 Date: Sun, 5 May 2019 11:03:12 +0800
   4 Subject: configfs: fix possible use-after-free in configfs_register_group
   5
   6 [ Upstream commit 35399f87e271f7cf3048eab00a421a6519ac8441 ]
   7
   8 In configfs_register_group(), if create_default_group() failed, we
   9 forget to unlink the group. It will left a invalid item in the parent list,
  10 which may trigger the use-after-free issue seen below:
  11
  12 BUG: KASAN: use-after-free in __list_add_valid+0xd4/0xe0 lib/list_debug.c:26
  13 Read of size 8 at addr ffff8881ef61ae20 by task syz-executor.0/5996
  14
  15 CPU: 1 PID: 5996 Comm: syz-executor.0 Tainted: G         C        5.0.0+ #5
  16 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
  17 Call Trace:
  18  __dump_stack lib/dump_stack.c:77 [inline]
  19  dump_stack+0xa9/0x10e lib/dump_stack.c:113
  20  print_address_description+0x65/0x270 mm/kasan/report.c:187
  21  kasan_report+0x149/0x18d mm/kasan/report.c:317
  22  __list_add_valid+0xd4/0xe0 lib/list_debug.c:26
  23  __list_add include/linux/list.h:60 [inline]
  24  list_add_tail include/linux/list.h:93 [inline]
  25  link_obj+0xb0/0x190 fs/configfs/dir.c:759
  26  link_group+0x1c/0x130 fs/configfs/dir.c:784
  27  configfs_register_group+0x56/0x1e0 fs/configfs/dir.c:1751
  28  configfs_register_default_group+0x72/0xc0 fs/configfs/dir.c:1834
  29  ? 0xffffffffc1be0000
  30  iio_sw_trigger_init+0x23/0x1000 [industrialio_sw_trigger]
  31  do_one_initcall+0xbc/0x47d init/main.c:887
  32  do_init_module+0x1b5/0x547 kernel/module.c:3456
  33  load_module+0x6405/0x8c10 kernel/module.c:3804
  34  __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
  35  do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
  36  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  37 RIP: 0033:0x462e99
  38 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 bc ff ff ff f7 d8 64 89 01 48
  39 RSP: 002b:00007f494ecbcc58 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
  40 RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99
  41 RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003
  42 RBP: 00007f494ecbcc70 R08: 0000000000000000 R09: 0000000000000000
  43 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f494ecbd6bc
  44 R13: 00000000004bcefa R14: 00000000006f6fb0 R15: 0000000000000004
  45
  46 Allocated by task 5987:
  47  set_track mm/kasan/common.c:87 [inline]
  48  __kasan_kmalloc.constprop.3+0xa0/0xd0 mm/kasan/common.c:497
  49  kmalloc include/linux/slab.h:545 [inline]
  50  kzalloc include/linux/slab.h:740 [inline]
  51  configfs_register_default_group+0x4c/0xc0 fs/configfs/dir.c:1829
  52  0xffffffffc1bd0023
  53  do_one_initcall+0xbc/0x47d init/main.c:887
  54  do_init_module+0x1b5/0x547 kernel/module.c:3456
  55  load_module+0x6405/0x8c10 kernel/module.c:3804
  56  __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
  57  do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
  58  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  59
  60 Freed by task 5987:
  61  set_track mm/kasan/common.c:87 [inline]
  62  __kasan_slab_free+0x130/0x180 mm/kasan/common.c:459
  63  slab_free_hook mm/slub.c:1429 [inline]
  64  slab_free_freelist_hook mm/slub.c:1456 [inline]
  65  slab_free mm/slub.c:3003 [inline]
  66  kfree+0xe1/0x270 mm/slub.c:3955
  67  configfs_register_default_group+0x9a/0xc0 fs/configfs/dir.c:1836
  68  0xffffffffc1bd0023
  69  do_one_initcall+0xbc/0x47d init/main.c:887
  70  do_init_module+0x1b5/0x547 kernel/module.c:3456
  71  load_module+0x6405/0x8c10 kernel/module.c:3804
  72  __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
  73  do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
  74  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  75
  76 The buggy address belongs to the object at ffff8881ef61ae00
  77  which belongs to the cache kmalloc-192 of size 192
  78 The buggy address is located 32 bytes inside of
  79  192-byte region [ffff8881ef61ae00, ffff8881ef61aec0)
  80 The buggy address belongs to the page:
  81 page:ffffea0007bd8680 count:1 mapcount:0 mapping:ffff8881f6c03000 index:0xffff8881ef61a700
  82 flags: 0x2fffc0000000200(slab)
  83 raw: 02fffc0000000200 ffffea0007ca4740 0000000500000005 ffff8881f6c03000
  84 raw: ffff8881ef61a700 000000008010000c 00000001ffffffff 0000000000000000
  85 page dumped because: kasan: bad access detected
  86
  87 Memory state around the buggy address:
  88  ffff8881ef61ad00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  89  ffff8881ef61ad80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
  90 >ffff8881ef61ae00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  91                                ^
  92  ffff8881ef61ae80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
  93  ffff8881ef61af00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  94
  95 Fixes: 5cf6a51e6062 ("configfs: allow dynamic group creation")
  96 Reported-by: Hulk Robot <hulkci@huawei.com>
  97 Signed-off-by: YueHaibing <yuehaibing@huawei.com>
  98 Signed-off-by: Christoph Hellwig <hch@lst.de>
  99 Signed-off-by: Sasha Levin <sashal@kernel.org>
 100 ---
 101  fs/configfs/dir.c | 17 ++++++++++++-----
 102  1 file changed, 12 insertions(+), 5 deletions(-)
 103
 104 diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
 105 index 39843fa7e11b..920d350df37b 100644
 106 --- a/fs/configfs/dir.c
 107 +++ b/fs/configfs/dir.c
 108 @@ -1755,12 +1755,19 @@ int configfs_register_group(struct config_group *parent_group,
 109
 110         inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
 111         ret = create_default_group(parent_group, group);
 112 -       if (!ret) {
 113 -               spin_lock(&configfs_dirent_lock);
 114 -               configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
 115 -               spin_unlock(&configfs_dirent_lock);
 116 -       }
 117 +       if (ret)
 118 +               goto err_out;
 119 +
 120 +       spin_lock(&configfs_dirent_lock);
 121 +       configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
 122 +       spin_unlock(&configfs_dirent_lock);
 123 +       inode_unlock(d_inode(parent));
 124 +       return 0;
 125 +err_out:
 126         inode_unlock(d_inode(parent));
 127 +       mutex_lock(&subsys->su_mutex);
 128 +       unlink_group(group);
 129 +       mutex_unlock(&subsys->su_mutex);
 130         return ret;
 131  }
 132  EXPORT_SYMBOL(configfs_register_group);
 133 --
 134 2.20.1
 135