From: OGAWA Hirofumi hirofumi@mail.parknet.co.jp
[ Upstream commit b1b65750b8db67834482f758fc385bfa7560d228 ]
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: Sasha Levin sashal@kernel.org --- fs/fat/inode.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 5e87b9aa7ba6..944fff1ef536 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1422,6 +1422,12 @@ 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: