ntfs3: fix out-of-bounds read in ntfs_dir_emit() and hdr_find_e()

The bounds check in ntfs_dir_emit() compares fname->name_len (a
character count) against e->size (a byte count) without accounting
for the 2-byte-per-character UTF-16LE encoding or the ATTR_FILE_NAME
header size:

  if (fname->name_len + sizeof(struct NTFS_DE) > le16_to_cpu(e->size))

This computes: name_len + 16 > e_size

The correct check must account for the ATTR_FILE_NAME header (66 bytes
before the name) and the UTF-16LE character size (2 bytes each):

  sizeof(NTFS_DE) + offsetof(ATTR_FILE_NAME, name) +
  name_len * sizeof(short) > e_size

Which computes: 16 + 66 + name_len * 2 > e_size

The correct calculation already exists as fname_full_size() in ntfs.h
and is used in cmp_fnames(), namei.c, and fslog.c, but was not used
in the readdir path.

A crafted NTFS image with an index entry containing a small e->size
but large fname->name_len bypasses the current check, causing
ntfs_utf16_to_nls() to read past the entry boundary.

Additionally, add a key_size validation in hdr_find_e() to ensure the
declared key_size does not exceed the available entry data, preventing
comparison functions from reading past entry boundaries on the lookup
path.

Signed-off-by: Alessandro Schino <7991aleschino@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

diff --git a/fs/ntfs3/dir.c b/fs/ntfs3/dir.c
index a052ba9250e739a5ce424d5c3cad6b9c4cde6ae1..873d52233003a1123849cc8aa3e4a67db8cc33de 100644 (file)
--- a/fs/ntfs3/dir.c
+++ b/fs/ntfs3/dir.c
@@ -305,7 +305,9 @@ static inline bool ntfs_dir_emit(struct ntfs_sb_info *sbi,
        if (sbi->options->nohidden && (fname->dup.fa & FILE_ATTRIBUTE_HIDDEN))
                return true;
 
-       if (fname->name_len + sizeof(struct NTFS_DE) > le16_to_cpu(e->size))
+       if (sizeof(struct NTFS_DE) +
+           offsetof(struct ATTR_FILE_NAME, name) +
+           fname->name_len * sizeof(short) > le16_to_cpu(e->size))
                return true;
 
        name_len = ntfs_utf16_to_nls(sbi, fname->name, fname->name_len, name,

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 7d6bb14893e9dd1b495ae377c66bc97176e4958d..2b439ac0435632646f83471a0944ad7f42e641cf 100644 (file)
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -789,6 +789,10 @@ fill_table:
 binary_search:
        e_key_len = le16_to_cpu(e->key_size);
 
+       /* Validate key_size fits within the entry data area. */
+       if (e_key_len > le16_to_cpu(e->size) - sizeof(struct NTFS_DE))
+               return NULL;
+
        diff2 = (*cmp)(key, key_len, e + 1, e_key_len, ctx);
        if (diff2 > 0) {
                if (found) {