ntfs: fix MFT bitmap scan 2^32 boundary check

NTFS MFT record numbers are limited to the 32-bit range, and
ntfs_mft_record_layout() rejects mft_no >= 2^32.  The free-MFT-record
bitmap scan in ntfs_mft_bitmap_find_and_alloc_free_rec_nolock() also
guards against this overflow but uses a strict greater than comparison,
allowing record number 2^32 itself through this earlier check.

Every other 2^32 boundary check in fs/ntfs/mft.c uses '>=', so the
strict greater than here is both a real off-by-one and an internal
inconsistency.  A model with ll == 2^32 confirms the current check
accepts the value while the corrected check rejects it.

Use '>=' so the boundary matches the layout-time rejection and the
surrounding bitmap-scan checks.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index 729b259974eb05a7b343fe0d9c0030ee79641740..a7d10ee41b34476f569f30b66f6a0d436e410fa9 100644 (file)
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -1064,7 +1064,7 @@ static s64 ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(struct ntfs_volume *vo
                                b = ffz((unsigned long)*byte);
                                if (b < 8 && b >= (bit & 7)) {
                                        ll = data_pos + (bit & ~7ull) + b;
-                                       if (unlikely(ll > (1ll << 32))) {
+                                       if (unlikely(ll >= (1ll << 32))) {
                                                folio_unlock(folio);
                                                kunmap_local(buf);
                                                folio_put(folio);