Re: [PATCH] hfsplus: don't use BUG_ON() in hfsplus_create_attributes_file()

[Yangtao Li]

在 2025/7/1 01:18, Viacheslav Dubeyko 写道:
> On Wed, 2025-06-25 at 19:10 +0900, Tetsuo Handa wrote:
> > syzkaller can mount crafted filesystem images.
> > Don't crash the kernel when we can continue.
> >
> > Reported-by: syzbot <syzbot+1107451c16b9eb9d29e6@xxxxxxxxxxxxxxxxxxxxxxxxx>
> > Closes: https://syzkaller.appspot.com/bug?extid=1107451c16b9eb9d29e6
> > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> > ---
> >   fs/hfsplus/xattr.c | 6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
> > index 9a1a93e3888b..191767d4cf78 100644
> > --- a/fs/hfsplus/xattr.c
> > +++ b/fs/hfsplus/xattr.c
> > @@ -172,7 +172,11 @@ static int hfsplus_create_attributes_file(struct super_block *sb)
> >   		return PTR_ERR(attr_file);
> >   	}
> >   
> > -	BUG_ON(i_size_read(attr_file) != 0);
>
> So, it's something like unexpected situation here. Why do we have
> i_size_read(attr_file) != 0 here? It looks like hfsplus_create_attributes_file()
> was called in incorrect context. Probably, it's not the whole fix. Any ideas?

161         case HFSPLUS_VALID_ATTR_TREE:
162                 return 0;
163         case HFSPLUS_FAILED_ATTR_TREE:
164                 return -EOPNOTSUPP;
165         default:
166                 BUG();
167         }

I haven't delved into the implementation details of xattr yet, but there 
is a bug in this function. It seems that we should convert the bug to 
return EIO in another patch?

Otherwise LGTM.

Reviewed-by: Yangtao Li <frank.li@xxxxxxxx>

Thx,
Yangtao