Re: [PATCH] f2fs: fsverity: Truncate cache pages if set verity failed

From: Eric Biggers <ebiggers@kernel.org>
To: heyunlei <heyunlei@hihonor.com>
Cc: Chao Yu <chao@kernel.org>,
	jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net,
	bintian.wang@hihonor.com, linux-fscrypt@vger.kernel.org
Subject: Re: [PATCH] f2fs: fsverity: Truncate cache pages if set verity failed
Date: Wed, 24 Feb 2021 15:11:12 -0800	[thread overview]
Message-ID: <YDbdEEcEV5bzgtL6@sol.localdomain> (raw)
In-Reply-To: <YDbbGSsd6ibKOpzT@sol.localdomain>

On Wed, Feb 24, 2021 at 03:02:52PM -0800, Eric Biggers wrote:
> Hi Yunlei,
> 
> On Wed, Feb 24, 2021 at 09:16:24PM +0800, Chao Yu wrote:
> > Hi Yunlei,
> > 
> > On 2021/2/23 19:24, heyunlei wrote:
> > > If file enable verity failed, should truncate anything wrote
> > > past i_size, including cache pages.
> > 
> > +Cc Eric,
> > 
> > After failure of enabling verity, we will see verity metadata if we truncate
> > file to larger size later?
> > 
> > Thanks,
> > 
> > > 
> > > Signed-off-by: heyunlei <heyunlei@hihonor.com>
> > > ---
> > >   fs/f2fs/verity.c | 4 +++-
> > >   1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c
> > > index 054ec852b5ea..f1f9b9361a71 100644
> > > --- a/fs/f2fs/verity.c
> > > +++ b/fs/f2fs/verity.c
> > > @@ -170,8 +170,10 @@ static int f2fs_end_enable_verity(struct file *filp, const void *desc,
> > >   	}
> > >   	/* If we failed, truncate anything we wrote past i_size. */
> > > -	if (desc == NULL || err)
> > > +	if (desc == NULL || err) {
> > > +		truncate_inode_pages(inode->i_mapping, inode->i_size);
> > >   		f2fs_truncate(inode);
> > > +	}
> > >   	clear_inode_flag(inode, FI_VERITY_IN_PROGRESS);
> > > 
> 
> This looks good; thanks for finding this.  You can add:
> 
> 	Reviewed-by: Eric Biggers <ebiggers@google.com>
> 
> I thought that f2fs_truncate() would truncate pagecache pages too, but in fact
> that's not the case.
> 
> ext4_end_enable_verity() has the same bug too.  Can you please send a patch for
> that too (to linux-ext4)?
> 

Also please include the following tags in the f2fs patch:

	Fixes: 95ae251fe828 ("f2fs: add fs-verity support")
	Cc: <stable@vger.kernel.org> # v5.4+

and in the ext4 patch:

	Fixes: c93d8f885809 ("ext4: add basic fs-verity support")
	Cc: <stable@vger.kernel.org> # v5.4+

- Eric