fs/ntfs3: Validate buffer length while parsing index

indx_read is called when we have some NTFS directory operations that
need more information from the index buffers. This adds a sanity check
to make sure the returned index buffer length is legit, or we may have
some out-of-bound memory accesses.

[  560.897595] BUG: KASAN: slab-out-of-bounds in hdr_find_e.isra.0+0x10c/0x320
[  560.898321] Read of size 2 at addr ffff888009497238 by task exp/245
[  560.898760]
[  560.899129] CPU: 0 PID: 245 Comm: exp Not tainted 6.0.0-rc6 Freescale#37
[  560.899505] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[  560.900170] Call Trace:
[  560.900407]  <TASK>
[  560.900732]  dump_stack_lvl+0x49/0x63
[  560.901108]  print_report.cold+0xf5/0x689
[  560.901395]  ? hdr_find_e.isra.0+0x10c/0x320
[  560.901716]  kasan_report+0xa7/0x130
[  560.901950]  ? hdr_find_e.isra.0+0x10c/0x320
[  560.902208]  __asan_load2+0x68/0x90
[  560.902427]  hdr_find_e.isra.0+0x10c/0x320
[  560.902846]  ? cmp_uints+0xe0/0xe0
[  560.903363]  ? cmp_sdh+0x90/0x90
[  560.903883]  ? ntfs_bread_run+0x190/0x190
[  560.904196]  ? rwsem_down_read_slowpath+0x750/0x750
[  560.904969]  ? ntfs_fix_post_read+0xe0/0x130
[  560.905259]  ? __kasan_check_write+0x14/0x20
[  560.905599]  ? up_read+0x1a/0x90
[  560.905853]  ? indx_read+0x22c/0x380
[  560.906096]  indx_find+0x2ef/0x470
[  560.906352]  ? indx_find_buffer+0x2d0/0x2d0
[  560.906692]  ? __kasan_kmalloc+0x88/0xb0
[  560.906977]  dir_search_u+0x196/0x2f0
[  560.907220]  ? ntfs_nls_to_utf16+0x450/0x450
[  560.907464]  ? __kasan_check_write+0x14/0x20
[  560.907747]  ? mutex_lock+0x8f/0xe0
[  560.907970]  ? __mutex_lock_slowpath+0x20/0x20
[  560.908214]  ? kmem_cache_alloc+0x143/0x4b0
[  560.908459]  ntfs_lookup+0xe0/0x100
[  560.908788]  __lookup_slow+0x116/0x220
[  560.909050]  ? lookup_fast+0x1b0/0x1b0
[  560.909309]  ? lookup_fast+0x13f/0x1b0
[  560.909601]  walk_component+0x187/0x230
[  560.909944]  link_path_walk.part.0+0x3f0/0x660
[  560.910285]  ? handle_lookup_down+0x90/0x90
[  560.910618]  ? path_init+0x642/0x6e0
[  560.911084]  ? percpu_counter_add_batch+0x6e/0xf0
[  560.912559]  ? __alloc_file+0x114/0x170
[  560.913008]  path_openat+0x19c/0x1d10
[  560.913419]  ? getname_flags+0x73/0x2b0
[  560.913815]  ? kasan_save_stack+0x3a/0x50
[  560.914125]  ? kasan_save_stack+0x26/0x50
[  560.914542]  ? __kasan_slab_alloc+0x6d/0x90
[  560.914924]  ? kmem_cache_alloc+0x143/0x4b0
[  560.915339]  ? getname_flags+0x73/0x2b0
[  560.915647]  ? getname+0x12/0x20
[  560.916114]  ? __x64_sys_open+0x4c/0x60
[  560.916460]  ? path_lookupat.isra.0+0x230/0x230
[  560.916867]  ? __isolate_free_page+0x2e0/0x2e0
[  560.917194]  do_filp_open+0x15c/0x1f0
[  560.917448]  ? may_open_dev+0x60/0x60
[  560.917696]  ? expand_files+0xa4/0x3a0
[  560.917923]  ? __kasan_check_write+0x14/0x20
[  560.918185]  ? _raw_spin_lock+0x88/0xdb
[  560.918409]  ? _raw_spin_lock_irqsave+0x100/0x100
[  560.918783]  ? _find_next_bit+0x4a/0x130
[  560.919026]  ? _raw_spin_unlock+0x19/0x40
[  560.919276]  ? alloc_fd+0x14b/0x2d0
[  560.919635]  do_sys_openat2+0x32a/0x4b0
[  560.920035]  ? file_open_root+0x230/0x230
[  560.920336]  ? __rcu_read_unlock+0x5b/0x280
[  560.920813]  do_sys_open+0x99/0xf0
[  560.921208]  ? filp_open+0x60/0x60
[  560.921482]  ? exit_to_user_mode_prepare+0x49/0x180
[  560.921867]  __x64_sys_open+0x4c/0x60
[  560.922128]  do_syscall_64+0x3b/0x90
[  560.922369]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[  560.923030] RIP: 0033:0x7f7dff2e4469
[  560.923681] Code: 00 f3 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 24 088
[  560.924451] RSP: 002b:00007ffd41a210b8 EFLAGS: 00000206 ORIG_RAX: 0000000000000002
[  560.925168] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7dff2e4469
[  560.925655] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007ffd41a211f0
[  560.926085] RBP: 00007ffd41a252a0 R08: 00007f7dff60fba0 R09: 00007ffd41a25388
[  560.926405] R10: 0000000000400b80 R11: 0000000000000206 R12: 00000000004004e0
[  560.926867] R13: 00007ffd41a25380 R14: 0000000000000000 R15: 0000000000000000
[  560.927241]  </TASK>
[  560.927491]
[  560.927755] Allocated by task 245:
[  560.928409]  kasan_save_stack+0x26/0x50
[  560.929271]  __kasan_kmalloc+0x88/0xb0
[  560.929778]  __kmalloc+0x192/0x320
[  560.930023]  indx_read+0x249/0x380
[  560.930224]  indx_find+0x2a2/0x470
[  560.930695]  dir_search_u+0x196/0x2f0
[  560.930892]  ntfs_lookup+0xe0/0x100
[  560.931115]  __lookup_slow+0x116/0x220
[  560.931323]  walk_component+0x187/0x230
[  560.931570]  link_path_walk.part.0+0x3f0/0x660
[  560.931791]  path_openat+0x19c/0x1d10
[  560.932008]  do_filp_open+0x15c/0x1f0
[  560.932226]  do_sys_openat2+0x32a/0x4b0
[  560.932413]  do_sys_open+0x99/0xf0
[  560.932709]  __x64_sys_open+0x4c/0x60
[  560.933417]  do_syscall_64+0x3b/0x90
[  560.933776]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[  560.934235]
[  560.934486] The buggy address belongs to the object at ffff888009497000
[  560.934486]  which belongs to the cache kmalloc-512 of size 512
[  560.935239] The buggy address is located 56 bytes to the right of
[  560.935239]  512-byte region [ffff888009497000, ffff888009497200)
[  560.936153]
[  560.937326] The buggy address belongs to the physical page:
[  560.938228] page:0000000062a3dfae refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9496
[  560.939616] head:0000000062a3dfae order:1 compound_mapcount:0 compound_pincount:0
[  560.940219] flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
[  560.942702] raw: 000fffffc0010200 ffffea0000164f80 dead000000000005 ffff888001041c80
[  560.943932] raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
[  560.944568] page dumped because: kasan: bad access detected
[  560.945735]
[  560.946112] Memory state around the buggy address:
[  560.946870]  ffff888009497100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  560.947242]  ffff888009497180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  560.947611] >ffff888009497200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  560.947915]                                         ^
[  560.948249]  ffff888009497280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  560.948687]  ffff888009497300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Signed-off-by: Edward Lo <[email protected]>
Signed-off-by: Konstantin Komarov <[email protected]>

fs/ntfs3/index.c

@@ -1017,6 +1017,12 @@ int indx_read(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
 		err = 0;
 	}
 
+	/* check for index header length */
+	if (offsetof(struct INDEX_BUFFER, ihdr) + ib->ihdr.used > bytes) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	in->index = ib;
 	*node = in;