Commit b1b65750 authored Jun 04, 2020 by OGAWA Hirofumi Committed by Linus Torvalds Jun 04, 2020

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.

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>

parent ada4ab7a

fs/fat/inode.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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:

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