f2fs: fix to do sanity check with reserved blkaddr of inline inode

As Wen Xu reported in bugzilla, after image was injected with random data
by fuzzing, inline inode would contain invalid reserved blkaddr, then
during inline conversion, we will encounter illegal memory accessing
reported by KASAN, the root cause of this is when writing out converted
inline page, we will use invalid reserved blkaddr to update sit bitmap,
result in accessing memory beyond sit bitmap boundary.

In order to fix this issue, let's do sanity check with reserved block
address of inline inode to avoid above condition.

https://bugzilla.kernel.org/show_bug.cgi?id=200179

[ 1428.846352] BUG: KASAN: use-after-free in update_sit_entry+0x80/0x7f0
[ 1428.846618] Read of size 4 at addr ffff880194483540 by task a.out/2741

[ 1428.846855] CPU: 0 PID: 2741 Comm: a.out Tainted: G        W         4.17.0+ #1
[ 1428.846858] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 1428.846860] Call Trace:
[ 1428.846868]  dump_stack+0x71/0xab
[ 1428.846875]  print_address_description+0x6b/0x290
[ 1428.846881]  kasan_report+0x28e/0x390
[ 1428.846888]  ? update_sit_entry+0x80/0x7f0
[ 1428.846898]  update_sit_entry+0x80/0x7f0
[ 1428.846906]  f2fs_allocate_data_block+0x6db/0xc70
[ 1428.846914]  ? f2fs_get_node_info+0x14f/0x590
[ 1428.846920]  do_write_page+0xc8/0x150
[ 1428.846928]  f2fs_outplace_write_data+0xfe/0x210
[ 1428.846935]  ? f2fs_do_write_node_page+0x170/0x170
[ 1428.846941]  ? radix_tree_tag_clear+0xff/0x130
[ 1428.846946]  ? __mod_node_page_state+0x22/0xa0
[ 1428.846951]  ? inc_zone_page_state+0x54/0x100
[ 1428.846956]  ? __test_set_page_writeback+0x336/0x5d0
[ 1428.846964]  f2fs_convert_inline_page+0x407/0x6d0
[ 1428.846971]  ? f2fs_read_inline_data+0x3b0/0x3b0
[ 1428.846978]  ? __get_node_page+0x335/0x6b0
[ 1428.846987]  f2fs_convert_inline_inode+0x41b/0x500
[ 1428.846994]  ? f2fs_convert_inline_page+0x6d0/0x6d0
[ 1428.847000]  ? kasan_unpoison_shadow+0x31/0x40
[ 1428.847005]  ? kasan_kmalloc+0xa6/0xd0
[ 1428.847024]  f2fs_file_mmap+0x79/0xc0
[ 1428.847029]  mmap_region+0x58b/0x880
[ 1428.847037]  ? arch_get_unmapped_area+0x370/0x370
[ 1428.847042]  do_mmap+0x55b/0x7a0
[ 1428.847048]  vm_mmap_pgoff+0x16f/0x1c0
[ 1428.847055]  ? vma_is_stack_for_current+0x50/0x50
[ 1428.847062]  ? __fsnotify_update_child_dentry_flags.part.1+0x160/0x160
[ 1428.847068]  ? do_sys_open+0x206/0x2a0
[ 1428.847073]  ? __fget+0xb4/0x100
[ 1428.847079]  ksys_mmap_pgoff+0x278/0x360
[ 1428.847085]  ? find_mergeable_anon_vma+0x50/0x50
[ 1428.847091]  do_syscall_64+0x73/0x160
[ 1428.847098]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1428.847102] RIP: 0033:0x7fb1430766ba
[ 1428.847103] Code: 89 f5 41 54 49 89 fc 55 53 74 35 49 63 e8 48 63 da 4d 89 f9 49 89 e8 4d 63 d6 48 89 da 4c 89 ee 4c 89 e7 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 56 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 00
[ 1428.847162] RSP: 002b:00007ffc651d9388 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
[ 1428.847167] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fb1430766ba
[ 1428.847170] RDX: 0000000000000001 RSI: 0000000000001000 RDI: 0000000000000000
[ 1428.847173] RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000000
[ 1428.847176] R10: 0000000000008002 R11: 0000000000000246 R12: 0000000000000000
[ 1428.847179] R13: 0000000000001000 R14: 0000000000008002 R15: 0000000000000000

[ 1428.847252] Allocated by task 2683:
[ 1428.847372]  kasan_kmalloc+0xa6/0xd0
[ 1428.847380]  kmem_cache_alloc+0xc8/0x1e0
[ 1428.847385]  getname_flags+0x73/0x2b0
[ 1428.847390]  user_path_at_empty+0x1d/0x40
[ 1428.847395]  vfs_statx+0xc1/0x150
[ 1428.847401]  __do_sys_newlstat+0x7e/0xd0
[ 1428.847405]  do_syscall_64+0x73/0x160
[ 1428.847411]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[ 1428.847466] Freed by task 2683:
[ 1428.847566]  __kasan_slab_free+0x137/0x190
[ 1428.847571]  kmem_cache_free+0x85/0x1e0
[ 1428.847575]  filename_lookup+0x191/0x280
[ 1428.847580]  vfs_statx+0xc1/0x150
[ 1428.847585]  __do_sys_newlstat+0x7e/0xd0
[ 1428.847590]  do_syscall_64+0x73/0x160
[ 1428.847596]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[ 1428.847648] The buggy address belongs to the object at ffff880194483300
                which belongs to the cache names_cache of size 4096
[ 1428.847946] The buggy address is located 576 bytes inside of
                4096-byte region [ffff880194483300, ffff880194484300)
[ 1428.848234] The buggy address belongs to the page:
[ 1428.848366] page:ffffea0006512000 count:1 mapcount:0 mapping:ffff8801f3586380 index:0x0 compound_mapcount: 0
[ 1428.848606] flags: 0x17fff8000008100(slab|head)
[ 1428.848737] raw: 017fff8000008100 dead000000000100 dead000000000200 ffff8801f3586380
[ 1428.848931] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
[ 1428.849122] page dumped because: kasan: bad access detected

[ 1428.849305] Memory state around the buggy address:
[ 1428.849436]  ffff880194483400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1428.849620]  ffff880194483480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1428.849804] >ffff880194483500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1428.849985]                                            ^
[ 1428.850120]  ffff880194483580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1428.850303]  ffff880194483600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1428.850498] ==================================================================

Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
