linux-kernel - [PATCH v2] clk: renesas: cpg-mssr: Fix use after free if cpg_mssr_common

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Date:   Fri, 23 Dec 2022 17:40:17 +0300
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Brandt <chris.brandt@...esas.com>
Cc:     Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: [PATCH v2] clk: renesas: cpg-mssr: Fix use after free if cpg_mssr_common_init() failed

If cpg_mssr_common_init() fails after assigning priv to global variable
cpg_mssr_priv, it deallocates priv, but cpg_mssr_priv keeps dangling
pointer that potentially can be used later.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1f7db7bbf031 ("clk: renesas: cpg-mssr: Add early clock support")
Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
v2: Move cpg_mssr_priv assignment just before return 0; instead of
clearing it as Geert Uytterhoeven <geert@...ux-m68k.org> suggested.
 drivers/clk/renesas/renesas-cpg-mssr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c
index 1a0cdf001b2f..5dce9779324d 100644
--- a/drivers/clk/renesas/renesas-cpg-mssr.c
+++ b/drivers/clk/renesas/renesas-cpg-mssr.c
@@ -989,7 +989,6 @@ static int __init cpg_mssr_common_init(struct device *dev,
 		goto out_err;
 	}
 
-	cpg_mssr_priv = priv;
 	priv->num_core_clks = info->num_total_core_clks;
 	priv->num_mod_clks = info->num_hw_mod_clks;
 	priv->last_dt_core_clk = info->last_dt_core_clk;
@@ -1019,6 +1018,8 @@ static int __init cpg_mssr_common_init(struct device *dev,
 	if (error)
 		goto out_err;
 
+	cpg_mssr_priv = priv;
+
 	return 0;
 
 out_err:
-- 
2.7.4