Re: [PATCH] jfs: fix GPF in diFree

[Dave Kleikamp]

On 6/23/21 11:38 AM, Pavel Skripkin wrote:
> On Wed, 23 Jun 2021 09:13:07 -0500
> Dave Kleikamp <dave.kleikamp@xxxxxxxxxx> wrote:
>
> > On 6/6/21 9:24 AM, Pavel Skripkin wrote:
> > > Avoid passing inode with
> > > JFS_SBI(inode->i_sb)->ipimap == NULL to
> > > diFree()[1]. GFP will appear:
> >
> > I'm a little curious how we get as far as creating and freeing
> > non-special inodes if ipimap == NULL.
> >
> > > 	struct inode *ipimap = JFS_SBI(ip->i_sb)->ipimap;
> > > 	struct inomap *imap = JFS_IP(ipimap)->i_imap;
> > >
> > > JFS_IP() will return invalid pointer when ipimap == NULL
> > >
> > > Call Trace:
> > >    diFree+0x13d/0x2dc0 fs/jfs/jfs_imap.c:853 [1]
> > >    jfs_evict_inode+0x2c9/0x370 fs/jfs/inode.c:154
> > >    evict+0x2ed/0x750 fs/inode.c:578
> > >    iput_final fs/inode.c:1654 [inline]
> > >    iput.part.0+0x3fe/0x820 fs/inode.c:1680
> > >    iput+0x58/0x70 fs/inode.c:1670
> >
> > Is there more to the stack trace? Is this part of a failed mount()?
>
> Hi, Dave!
>
> Yes, it was caused by mount fail. Log:
>
> [  924.076873][ T8430] jfs_mount: diMount(ipaimap) failed w/rc = -5
>
> So, it's errout21 label in jfs_mount(). I guess, It's early failure and
> some fields wasn't initialized properly. I don't really remember my
> debug results, because it was a long time ago, but I can do some debug
> work again if needed!

Thanks. I don't want to ask you to spend any more time on this. Sorry I 
didn't get back sooner. Thanks for the fix!

Shaggy

> Thanks for feedback!
>
> > > Reported-and-tested-by:
> > > syzbot+0a89a7b56db04c21a656@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>ipimap == NULL
> >
> > I don't doubt that this happened, so I'll apply the patch which is
> > obviously safe.
> >
> > > ---
> > >    fs/jfs/inode.c | 3 ++-
> > >    1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/jfs/inode.c b/fs/jfs/inode.c
> > > index 6f65bfa9f18d..b0eb9c85eea0 100644
> > > --- a/fs/jfs/inode.c
> > > +++ b/fs/jfs/inode.c
> > > @@ -151,7 +151,8 @@ void jfs_evict_inode(struct inode *inode)
> > >    			if (test_cflag(COMMIT_Freewmap, inode))
> > >    				jfs_free_zero_link(inode);
> > >    
> > > -			diFree(inode);
> > > +			if (JFS_SBI(inode->i_sb)->ipimap)
> > > +				diFree(inode);
> > >    
> > >    			/*
> > >    			 * Free the inode from the quota
> > > allocation.
>
>
>
>
> With regards,
> Pavel Skripkin