linux-kernel - [PATCH AUTOSEL 4.19 03/21] gfs2: Free rd_bits later in gfs2_clear

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Message-Id: <20201110035541.424648-3-sashal@kernel.org>
Date:   Mon,  9 Nov 2020 22:55:23 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Bob Peterson <rpeterso@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Sasha Levin <sashal@...nel.org>, cluster-devel@...hat.com
Subject: [PATCH AUTOSEL 4.19 03/21] gfs2: Free rd_bits later in gfs2_clear_rgrpd to fix use-after-free

From: Bob Peterson <rpeterso@...hat.com>

[ Upstream commit d0f17d3883f1e3f085d38572c2ea8edbd5150172 ]

Function gfs2_clear_rgrpd calls kfree(rgd->rd_bits) before calling
return_all_reservations, but return_all_reservations still dereferences
rgd->rd_bits in __rs_deltree.  Fix that by moving the call to kfree below the
call to return_all_reservations.

Signed-off-by: Bob Peterson <rpeterso@...hat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/gfs2/rgrp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index c94c4ac1ae78b..1686a40099f21 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -739,9 +739,9 @@ void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
 		}
 
 		gfs2_free_clones(rgd);
+		return_all_reservations(rgd);
 		kfree(rgd->rd_bits);
 		rgd->rd_bits = NULL;
-		return_all_reservations(rgd);
 		kmem_cache_free(gfs2_rgrpd_cachep, rgd);
 	}
 }
-- 
2.27.0