From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> mainline inclusion from mainline-v5.8-rc1 commit b1b65750b8db67834482f758fc385bfa7560d228 category: bugfix bugzilla: 36873 CVE: NA --------------------------- 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: Zheng Bin <zhengbin13@huawei.com> Reviewed-by: zhangyi (F) <yi.zhang@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- fs/fat/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 70d37a5fd72c..607e1d124062 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1519,6 +1519,12 @@ static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b, 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: -- 2.25.1