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Date:   Wed, 04 Jan 2023 23:33:50 +0100
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Linus Torvalds" <torvalds@linux-foundation.org>
Cc:     syzbot <syzbot+7bb7cd3595533513a9e7@syzkaller.appspotmail.com>,
        "Andrew Morton" <akpm@linux-foundation.org>,
        christian.brauner@ubuntu.com,
        "Damien Le Moal" <damien.lemoal@opensource.wdc.com>,
        jlayton@kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        "Matthew Wilcox" <willy@infradead.org>,
        ZhangPeng <zhangpeng362@huawei.com>,
        "Viacheslav Dubeyko" <slava@dubeyko.com>,
        linux-m68k@lists.linux-m68k.org
Subject: Re: [syzbot] [hfs?] WARNING in hfs_write_inode
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On Wed, Jan 4, 2023, at 20:06, Linus Torvalds wrote:
>
> I suspect this code is basically all dead. From what I can tell, hfs
> only gets updates for
>
>  (a) syzbot reports
>
>  (b) vfs interface changes

There is clearly no new work going into it, and most data exchange
with MacOS would use HFS+, but I think there are still some users.

> and the last real changes seem to have been by Ernesto A. Fern=C3=A1nd=
ez
> back in 2018.
>
> Hmm. Looking at that code, we have another bug in there, introduced by
> an earlier fix for a similar issue: commit 8d824e69d9f3 ("hfs: fix OOB
> Read in __hfs_brec_find") added
>
> +       if (HFS_I(main_inode)->cat_key.CName.len > HFS_NAMELEN)
> +               return -EIO;
>
> but it's after hfs_find_init(), so it should actually have done a
> hfs_find_exit() to not leak memory.
>
> So we should probably fix that too.
>
> Something like this ENTIRELY UNTESTED patch?
>
> Do we have anybody who looks at hfs?

Adding Viacheslav Dubeyko to Cc, he's at least been reviewing
patches for HFS and HFS+ somewhat recently. The linux-m68k
list may have some users dual-booting old MacOS.

Viacheslav, see the start of the thread at
https://lore.kernel.org/lkml/000000000000dbce4e05f170f289@google.com/

     Arnd