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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2020-06-04 16:50:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 19:06:25 -0700
commitb1b65750b8db67834482f758fc385bfa7560d228 (patch)
tree7fda49892d330f38bc4d654c399429b2d79181f2 /fs/fat
parentada4ab7af1a67db7eb8596709071a97afb2bf7de (diff)
downloadlinux-b1b65750b8db67834482f758fc385bfa7560d228.tar.bz2
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>
Diffstat (limited to 'fs/fat')
-rw-r--r--fs/fat/inode.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index e6e68b2274a5..a0cf99debb1e 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: