From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Subject: fat: don't allow to mount if the FAT length == 0 If FAT length == 0, the image doesn't have any data. And it can be the cause of overlapping the root dir and FAT entries. Also Windows treats it as invalid format. Link: http://lkml.kernel.org/r/87r1wz8mrd.fsf@xxxxxxxxxxxxxxxxxx Reported-by: syzbot+6f1624f937d9d6911e2d@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/fat/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/fat/inode.c~fat-dont-allow-to-mount-if-the-fat-length-==-0 +++ a/fs/fat/inode.c @@ -1519,6 +1519,12 @@ static int fat_read_bpb(struct super_blo goto out; } + if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) { + if (!silent) + fat_msg(sb, KERN_ERR, "bogus number of FAT sectors"); + goto out; + } + error = 0; out: _
