[PATCH 8/8] fs/ntfs3: Fix shift-out-of-bounds in ntfs_fill_super

[Konstantin Komarov <almaz.alexandrovich@paragon-software.com>]

Reported-by: syzbot+478c1bf0e6bf4a8f3a04@syzkaller.appspotmail.com
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
---
  fs/ntfs3/ntfs_fs.h |  2 ++
  fs/ntfs3/super.c   | 26 ++++++++++++++++++++------
  2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index 629403ede6e5..788567d71d93 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -42,9 +42,11 @@ enum utf16_endian;
  #define MINUS_ONE_T            ((size_t)(-1))
  /* Biggest MFT / smallest cluster */
  #define MAXIMUM_BYTES_PER_MFT        4096
+#define MAXIMUM_SHIFT_BYTES_PER_MFT    12
  #define NTFS_BLOCKS_PER_MFT_RECORD    (MAXIMUM_BYTES_PER_MFT / 512)

  #define MAXIMUM_BYTES_PER_INDEX        4096
+#define MAXIMUM_SHIFT_BYTES_PER_INDEX    12
  #define NTFS_BLOCKS_PER_INODE        (MAXIMUM_BYTES_PER_INDEX / 512)

  /* NTFS specific error code when fixup failed. */
diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 0034952b9ccd..34ebfaa8fbab 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -905,9 +905,17 @@ static int ntfs_init_from_boot(struct super_block 
*sb, u32 sector_size,
          goto out;
      }

-    sbi->record_size = record_size =
-        boot->record_size < 0 ? 1 << (-boot->record_size) :
-                    (u32)boot->record_size << cluster_bits;
+    if (boot->record_size >= 0) {
+        record_size = (u32)boot->record_size << cluster_bits;
+    } else if (-boot->record_size <= MAXIMUM_SHIFT_BYTES_PER_MFT) {
+        record_size = 1u << (-boot->record_size);
+    } else {
+        ntfs_err(sb, "%s: invalid record size %d.", hint,
+             boot->record_size);
+        goto out;
+    }
+
+    sbi->record_size = record_size;
      sbi->record_bits = blksize_bits(record_size);
      sbi->attr_size_tr = (5 * record_size >> 4); // ~320 bytes

@@ -924,9 +932,15 @@ static int ntfs_init_from_boot(struct super_block 
*sb, u32 sector_size,
          goto out;
      }

-    sbi->index_size = boot->index_size < 0 ?
-                  1u << (-boot->index_size) :
-                  (u32)boot->index_size << cluster_bits;
+    if (boot->index_size >= 0) {
+        sbi->index_size = (u32)boot->index_size << cluster_bits;
+    } else if (-boot->index_size <= MAXIMUM_SHIFT_BYTES_PER_INDEX) {
+        sbi->index_size = 1u << (-boot->index_size);
+    } else {
+        ntfs_err(sb, "%s: invalid index size %d.", hint,
+             boot->index_size);
+        goto out;
+    }

      /* Check index record size. */
      if (sbi->index_size < SECTOR_SIZE || 
!is_power_of_2(sbi->index_size)) {
-- 
2.34.1