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| author | Bryam Vargas <hexlabsecurity@proton.me> | 2026-06-07 23:30:00 +0300 |
|---|---|---|
| committer | Namjae Jeon <linkinjeon@kernel.org> | 2026-06-08 16:58:00 +0300 |
| commit | 344b18f389f9934d59c7b0cf3d20541ea2e0da58 (patch) | |
| tree | d75d55f3709fa7953cb0c23d7821429b19408137 | |
| parent | 7d19e1ffee084c4f7d321a360c14ba43404f7cc8 (diff) | |
| download | linux-344b18f389f9934d59c7b0cf3d20541ea2e0da58.tar.xz | |
ntfs: bound the look-ahead attribute-list entry in ntfs_external_attr_find()
When resolving an attribute lookup with a non-zero @lowest_vcn,
ntfs_external_attr_find() peeks at the next $ATTRIBUTE_LIST entry to
decide whether to keep searching, but bounds that not-yet-validated
entry only with "(u8 *)next_al_entry + 6 < al_end" (which proves just
bytes 0..6 are in range) and "(u8 *)next_al_entry + length <= al_end"
with an attacker-controlled, non-8-aligned length. It then reads
next_al_entry->lowest_vcn (an __le64 at offset 8) and the name at
next_al_entry->name_offset, both of which can lie past al_end -- the
exact end of the kvmalloc'd attribute-list buffer (allocated at the
on-disk attr_list_size, no rounding). A crafted on-disk $ATTRIBUTE_LIST
whose last entry sits a few bytes before al_end therefore yields a slab
out-of-bounds read when the inode is read.
Validate the look-ahead entry with ntfs_attr_list_entry_is_valid() (added
in patch 1/3) before dereferencing lowest_vcn and the name, so the same
fixed-header, length and name bounds the main attribute-list walk uses now
guard this read too.
Fixes: 1e9ea7e04472 ("Revert "fs: Remove NTFS classic"")
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
| -rw-r--r-- | fs/ntfs/attrib.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c index 2d675bf99ca7..1e0076ef81ef 100644 --- a/fs/ntfs/attrib.c +++ b/fs/ntfs/attrib.c @@ -1263,9 +1263,8 @@ find_attr_list_attr: * we have reached the right one or the search has failed. */ if (lowest_vcn && (u8 *)next_al_entry >= al_start && - (u8 *)next_al_entry + 6 < al_end && - (u8 *)next_al_entry + le16_to_cpu( - next_al_entry->length) <= al_end && + ntfs_attr_list_entry_is_valid(next_al_entry, + al_end) && le64_to_cpu(next_al_entry->lowest_vcn) <= lowest_vcn && next_al_entry->type == al_entry->type && |