linux-kernel - Re: [PATCH] bcachefs: fix oob in bch2_sb_clean_to

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Message-ID: <nq3ka3ovvksptfkl5c53c4yn54efhu6dtt356lrda2wg7xzwak@tutbtfe7eskb>
Date: Tue, 7 May 2024 21:21:16 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: Edward Adam Davis <eadavis@...com>
Cc: bfoster@...hat.com, linux-bcachefs@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzbot+c48865e11e7e893ec4ab@...kaller.appspotmail.com, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] bcachefs: fix oob in bch2_sb_clean_to_text

On Wed, May 08, 2024 at 09:11:37AM +0800, Edward Adam Davis wrote:
> On Tue, 7 May 2024 20:59:14 -0400, Kent Overstreet wrote:
> > > > diff --git a/fs/bcachefs/sb-clean.c b/fs/bcachefs/sb-clean.c
> > > > index 35ca3f138de6..194e55b11137 100644
> > > > --- a/fs/bcachefs/sb-clean.c
> > > > +++ b/fs/bcachefs/sb-clean.c
> > > > @@ -278,6 +278,17 @@ static int bch2_sb_clean_validate(struct bch_sb *sb,
> > > >  		return -BCH_ERR_invalid_sb_clean;
> > > >  	}
> > > > 
> > > > +	for (struct jset_entry *entry = clean->start;
> > > > +	     entry != vstruct_end(&clean->field);
> > > > +	     entry = vstruct_next(entry)) {
> > > > +		if ((void *) vstruct_next(entry) > vstruct_end(&clean->field)) {
> > > > +			prt_str(err, "entry type ");
> > > > +			bch2_prt_jset_entry_type(err, le16_to_cpu(entry->type));
> > > > +			prt_str(err, " overruns end of section");
> > > > +			return -BCH_ERR_invalid_sb_clean;
> > > > +		}
> > > > +	}
> > > > +
> > > The original judgment here is sufficient, there is no need to add this section of inspection.
> > 
> > No, we need to be able to print things that failed to validate so that
> > we see what went wrong.
> The follow check work fine, why add above check ?
>    1         if (vstruct_bytes(&clean->field) < sizeof(*clean)) {
>   268                 prt_printf(err, "wrong size (got %zu should be %zu)",
>     1                        vstruct_bytes(&clean->field), sizeof(*clean));
> 

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