ntfs: bound $AttrDef table walk to the loaded table size

ntfs_attr_find_in_attrdef() walks the in-memory $AttrDef table, but the
loop condition bounds only the start of each entry, not the whole entry:

	for (ad = vol->attrdef; (u8 *)ad - (u8 *)vol->attrdef <
			vol->attrdef_size && ad->type; ++ad)

struct attr_def is 160 bytes; the guard reads ad->type at offset 128 and
the loop body reads further fields. vol->attrdef is kvzalloc(i_size),
where i_size is the on-disk $AttrDef data size, checked in
load_and_init_attrdef() only as 0 < i_size <= 0x7fffffff. A volume whose
$AttrDef data size is smaller than one entry (e.g. 120 bytes) makes the
read of ad->type run past the allocation. Creating a file reaches this
through ntfs_attr_size_bounds_check() and reads out of bounds:

  BUG: KASAN: slab-out-of-bounds in ntfs_attr_find_in_attrdef+0x66/0xa0
  Read of size 4 at addr ffff888005833280 by task init/1
   ntfs_attr_find_in_attrdef
   ntfs_attr_size_bounds_check
   ntfs_attr_can_be_non_resident
   ntfs_attr_add

Require the whole entry to lie within attrdef_size in the loop guard, and
reject at mount a $AttrDef too small to hold one attr_def entry.

Fixes: 1e9ea7e04472 ("Revert "fs: Remove NTFS classic"")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Dennis Tighe <dennis.tighe@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

0 files changed, 0 insertions, 0 deletions