Re: [PATCH v2] xfs_db: release ip resource before returning from get_next_unlinked()

[Bill O'Donnell <bodonnel@redhat.com>]

On Wed, Aug 07, 2024 at 11:31:43AM -0700, Darrick J. Wong wrote:
> On Wed, Aug 07, 2024 at 01:15:54PM -0500, Bill O'Donnell wrote:
> > Fix potential memory leak in function get_next_unlinked(). Call
> > libxfs_irele(ip) before exiting.
> > 
> > Details:
> > Error: RESOURCE_LEAK (CWE-772):
> > xfsprogs-6.5.0/db/iunlink.c:51:2: alloc_arg: "libxfs_iget" allocates memory that is stored into "ip".
> > xfsprogs-6.5.0/db/iunlink.c:68:2: noescape: Resource "&ip->i_imap" is not freed or pointed-to in "libxfs_imap_to_bp".
> > xfsprogs-6.5.0/db/iunlink.c:76:2: leaked_storage: Variable "ip" going out of scope leaks the storage it points to.
> > #   74|   	libxfs_buf_relse(ino_bp);
> > #   75|
> > #   76|-> 	return ret;
> > #   77|   bad:
> > #   78|   	dbprintf(_("AG %u agino %u: %s\n"), agno, agino, strerror(error));
> > 
> > Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
> > ---
> > v2: cover the error case.
> > ---
> >  db/iunlink.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/db/iunlink.c b/db/iunlink.c
> > index d87562e3..bd973600 100644
> > --- a/db/iunlink.c
> > +++ b/db/iunlink.c
> > @@ -72,9 +72,12 @@ get_next_unlinked(
> >  	dip = xfs_buf_offset(ino_bp, ip->i_imap.im_boffset);
> >  	ret = be32_to_cpu(dip->di_next_unlinked);
> >  	libxfs_buf_relse(ino_bp);
> > +	libxfs_irele(ip);
> >  
> >  	return ret;
> >  bad:
> > +	libxfs_buf_relse(ino_bp);
> 
> What if we got here via the first 'goto bad' in this function?  We'll be
> feeding an uninitialized variable into libxfs_buf_relse.

ugh. Missed that, thanks.

-Bill


> 
> --D
> 
> > +	libxfs_irele(ip);
> >  	dbprintf(_("AG %u agino %u: %s\n"), agno, agino, strerror(error));
> >  	return NULLAGINO;
> >  }
> > -- 
> > 2.45.2
> > 
> > 
>