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

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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: 1e9ea7e044 ("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>
This commit is contained in:
Dennis Tighe 2026-08-25 21:44:24 -07:00 committed by Namjae Jeon
parent a79899ca38
commit c8504fc124
2 changed files with 4 additions and 4 deletions
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4
fs/ntfs/attrib.c
View File

@ -1737,8 +1737,8 @@ static struct attr_def *ntfs_attr_find_in_attrdef(const struct ntfs_volume *vol,
struct attr_def *ad;
WARN_ON(!type);
for (ad = vol->attrdef; (u8 *)ad - (u8 *)vol->attrdef <
vol->attrdef_size && ad->type; ++ad) {
for (ad = vol->attrdef; (u8 *)ad - (u8 *)vol->attrdef <=
vol->attrdef_size - (s32)sizeof(*ad) && ad->type; ++ad) {
/* We have not found it yet, carry on searching. */
if (likely(le32_to_cpu(ad->type) < le32_to_cpu(type)))
continue;

4
fs/ntfs/super.c
View File

@ -1241,9 +1241,9 @@ static bool load_and_init_attrdef(struct ntfs_volume *vol)
goto failed;
}
NInoSetSparseDisabled(NTFS_I(ino));
/* The size of FILE_AttrDef must be above 0 and fit inside 31 bits. */
/* FILE_AttrDef must hold at least one entry and fit inside 31 bits. */
i_size = i_size_read(ino);
if (i_size <= 0 || i_size > 0x7fffffff)
if (i_size < (s64)sizeof(struct attr_def) || i_size > 0x7fffffff)
goto iput_failed;
vol->attrdef = kvzalloc(i_size, GFP_NOFS);
if (!vol->attrdef)