linux-kernel - [BUG] fs: gfs2: possible null-pointer dereferences in gfs2_rgrp_bh

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Date:   Wed, 24 Jul 2019 16:50:03 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     rpeterso@...hat.com, agruenba@...hat.com
Cc:     cluster-devel@...hat.com, linux-kernel@...r.kernel.org
Subject: [BUG] fs: gfs2: possible null-pointer dereferences in
 gfs2_rgrp_bh_get()

In gfs2_rgrp_bh_get, there is an if statement on line 1191 to check 
whether "rgd->rd_bits[0].bi_bh" is NULL.
When "rgd->rd_bits[0].bi_bh" is NULL, it is used on line 1216:
     gfs2_rgrp_in(rgd, (rgd->rd_bits[0].bi_bh)->b_data);
and on line 1225:
     gfs2_rgrp_ondisk2lvb(..., rgd->rd_bits[0].bi_bh->b_data);
and on line 1228:
     if (!gfs2_rgrp_lvb_valid(rgd))

Note that in gfs2_rgrp_lvb_valid(rgd), there is a statement on line 1114:
     struct gfs2_rgrp *str = (struct gfs2_rgrp 
*)rgd->rd_bits[0].bi_bh->b_data;

Thus, possible null-pointer dereferences may occur.

These bugs are found by a static analysis tool STCheck written by us.
I do not know how to correctly fix these bugs, so I only report bugs.

Best wishes,
Jia-Ju Bai