| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 085/267] fat: dont allow to mount if the FAT length == 0 | Date | Fri, 19 Jun 2020 16:31:10 +0200 |
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From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
commit b1b65750b8db67834482f758fc385bfa7560d228 upstream.
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.
Reported-by: syzbot+6f1624f937d9d6911e2d@syzkaller.appspotmail.com Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Link: http://lkml.kernel.org/r/87r1wz8mrd.fsf@mail.parknet.co.jp Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/fat/inode.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/fat/inode.c +++ b/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:
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