NVD description
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list()
ni_create_attr_list() allocates a fixed buffer of al_aligned(record_size)
(== record_size) bytes and then walks every attribute of the primary MFT
record, writing one ATTR_LIST_ENTRY per attribute and advancing the cursor
by le_size(name_len), with no check against the end of the buffer; the
total size is only computed after the loop.
A minimum-size resident attribute occupies SIZEOF_RESIDENT (0x18 = 24)
bytes on disk, but an unnamed attribute expands to le_size(0) (0x20 = 32)
bytes in the list. Because the number of attributes in a record is not
bounded (mi_enum_attr() accepts arbitrarily many equal-type, nameless
minimum-size attributes), a crafted record packed with such attributes
produces a list larger than record_size and overflows the heap buffer.
This is reachable from a crafted, loop-mounted NTFS image: opening the file
and adding an attribute (e.g. via setxattr) drives ntfs_set_ea() ->
ni_insert_resident() -> ni_insert_attr() -> ni_ins_attr_ext() ->
ni_create_attr_list().
BUG: KASAN: slab-out-of-bounds in ni_create_attr_list+0xc48/0x1058
Write of size 4 at addr ffff000008984c00 by task setfattr/345
ni_create_attr_list+0xc48/0x1058
ni_ins_attr_ext+0x510/0x7c0
ni_insert_attr+0x3f8/0x70c
ni_insert_resident+0xc8/0x3b0
ntfs_set_ea+0x66c/0xd28
ntfs_setxattr+0x4d8/0x5b0
__arm64_sys_setxattr+0xa4/0x124
Allocated by task 345:
ni_create_attr_list+0x188/0x1058
The buggy address belongs to the cache kmalloc-1k of size 1024
(the write lands at object+1024).
Size the buffer from the actual attributes instead of assuming a single
record_size is always enough.
