Re: [PATCH] clk: fixed: fix double free in resource managed fixed-factor clock

From: Stephen Boyd <sboyd@kernel.org>
To: Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Michael Turquette <mturquette@baylibre.com>
Cc: linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
	dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org,
	Rob Clark <robdclark@chromium.org>,
	Daniel Palmer <daniel@0x0f.com>
Subject: Re: [PATCH] clk: fixed: fix double free in resource managed fixed-factor clock
Date: Wed, 07 Apr 2021 16:01:16 -0700	[thread overview]
Message-ID: <161783647690.3790633.7004111396421583619@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20210406230606.3007138-1-dmitry.baryshkov@linaro.org>

Quoting Dmitry Baryshkov (2021-04-06 16:06:06)
> devm_clk_hw_register_fixed_factor_release(), the release function for
> the devm_clk_hw_register_fixed_factor(), calls
> clk_hw_unregister_fixed_factor(), which will kfree() the clock. However
> after that the devres functions will also kfree the allocated data,
> resulting in double free/memory corruption. Just call
> clk_hw_unregister() instead, leaving kfree() to devres code.
> 
> Reported-by: Rob Clark <robdclark@chromium.org>
> Cc: Daniel Palmer <daniel@0x0f.com>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---

Applied to clk-fixes. I also squashed this in to cleanup that ugly cast.

---8<----

diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
index 390c16f321a6..4e4b6d367612 100644
--- a/drivers/clk/clk-fixed-factor.c
+++ b/drivers/clk/clk-fixed-factor.c
@@ -66,12 +66,14 @@ EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
 
 static void devm_clk_hw_register_fixed_factor_release(struct device *dev, void *res)
 {
+	struct clk_fixed_factor *fix = res;
+
 	/*
 	 * We can not use clk_hw_unregister_fixed_factor, since it will kfree()
 	 * the hw, resulting in double free. Just unregister the hw and let
 	 * devres code kfree() it.
 	 */
-	clk_hw_unregister(&((struct clk_fixed_factor *)res)->hw);
+	clk_hw_unregister(&fix->hw);
 }
 
 static struct clk_hw *
