linux-kernel - Re: [PATCH] VFS: check i_nlink count before trying to unlink

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Message-ID: <20240907190232.GI1049718@ZenIV>
Date: Sat, 7 Sep 2024 20:02:32 +0100
From: Al Viro <viro@...iv.linux.org.uk>
To: Ghanshyam Agrawal <ghanshyam1898@...il.com>
Cc: brauner@...nel.org, jack@...e.cz, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	syzbot+41b43444de86db4c5ed1@...kaller.appspotmail.com
Subject: Re: [PATCH] VFS: check i_nlink count before trying to unlink

On Sat, Sep 07, 2024 at 10:51:10PM +0530, Ghanshyam Agrawal wrote:
> Reported-by: syzbot+41b43444de86db4c5ed1@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=41b43444de86db4c5ed1
> Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@...il.com>

As far as I can tell, you have jfs_unlink() find and remove a directory
entry without any problems, then find that the damn thing had corrupted
inode link count (presumably due to creatively fucked up image).

IF that's the case, NAK.

vfs_unlink() is *NOT* the place to try and cope with that kind of crap.
What's more, having unlink(2) quietly succeed and do nothing to directory
is simply wrong.