hpfs: better test for errors
Mikulas Patocka [Thu, 4 Jul 2013 16:42:29 +0000 (18:42 +0200)]
commit 3ebacb05044f82c5f0bb456a894eb9dc57d0ed90 upstream.

The test if bitmap access is out of bound could errorneously pass if the
device size is divisible by 16384 sectors and we are asking for one bitmap
after the end.

Check for invalid size in the superblock. Invalid size could cause integer
overflows in the rest of the code.

Signed-off-by: Mikulas Patocka <mpatocka@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/hpfs/map.c
fs/hpfs/super.c

index 4acb19d..803d3da 100644 (file)
@@ -17,7 +17,8 @@ __le32 *hpfs_map_bitmap(struct super_block *s, unsigned bmp_block,
                         struct quad_buffer_head *qbh, char *id)
 {
        secno sec;
-       if (hpfs_sb(s)->sb_chk) if (bmp_block * 16384 > hpfs_sb(s)->sb_fs_size) {
+       unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
+       if (hpfs_sb(s)->sb_chk) if (bmp_block >= n_bands) {
                hpfs_error(s, "hpfs_map_bitmap called with bad parameter: %08x at %s", bmp_block, id);
                return NULL;
        }
index a0617e7..962e90c 100644 (file)
@@ -558,7 +558,13 @@ static int hpfs_fill_super(struct super_block *s, void *options, int silent)
        sbi->sb_cp_table = NULL;
        sbi->sb_c_bitmap = -1;
        sbi->sb_max_fwd_alloc = 0xffffff;
-       
+
+       if (sbi->sb_fs_size >= 0x80000000) {
+               hpfs_error(s, "invalid size in superblock: %08x",
+                       (unsigned)sbi->sb_fs_size);
+               goto bail4;
+       }
+
        /* Load bitmap directory */
        if (!(sbi->sb_bmp_dir = hpfs_load_bitmap_directory(s, le32_to_cpu(superblock->bitmaps))))
                goto bail4;