On Tue, May 15, 2018 at 07:08:24PM +0900, Tetsuo Handa wrote: > From f78a5fe168290cb9e009f4d907d04b5bfe277831 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Date: Tue, 15 May 2018 11:38:38 +0900 > Subject: [PATCH] hfsplus: don't return 0 when fill_super() failed > > syzbot is reporting NULL pointer dereference at mount_fs() [1]. > This is because hfsplus_fill_super() is by error returning 0 when > hfsplus_fill_super() detected invalid filesystem image, and mount_bdev() > is returning NULL because dget(s->s_root) == NULL if s->s_root == NULL, > and mount_fs() is accessing root->d_sb because IS_ERR(root) == false > if root == NULL. Fix this by returning -EINVAL when hfsplus_fill_super() > detected invalid filesystem image. > > [1] https://syzkaller.appspot.com/bug?id=21acb6850cecbc960c927229e597158cf35f33d0 > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Reported-by: syzbot <syzbot+01ffaf5d9568dd1609f7@xxxxxxxxxxxxxxxxxxxxxxxxx> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> It's been too long. I think I should give up on my patch. Maybe a review can help your version get merged. Reviewed-by: Ernesto A. Fernández <ernesto.mnd.fernandez@xxxxxxxxx> > --- > fs/hfsplus/super.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c > index 513c357..9e690ae 100644 > --- a/fs/hfsplus/super.c > +++ b/fs/hfsplus/super.c > @@ -524,8 +524,10 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent) > goto out_put_root; > if (!hfs_brec_read(&fd, &entry, sizeof(entry))) { > hfs_find_exit(&fd); > - if (entry.type != cpu_to_be16(HFSPLUS_FOLDER)) > + if (entry.type != cpu_to_be16(HFSPLUS_FOLDER)) { > + err = -EINVAL; > goto out_put_root; > + } > inode = hfsplus_iget(sb, be32_to_cpu(entry.folder.id)); > if (IS_ERR(inode)) { > err = PTR_ERR(inode); > -- > 1.8.3.1 > >
