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From:   Samuel Holland <samuel@sholland.org>
To:     Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Chen-Yu Tsai <wens@csie.org>,
        Jernej Skrabec <jernej.skrabec@gmail.com>
Cc:     linux-arm-kernel@lists.infradead.org, linux-rtc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev,
        Samuel Holland <samuel@sholland.org>
Subject: [PATCH 1/2] rtc: sun6i: Prevent an out-of-bounds read
Date:   Thu, 29 Dec 2022 12:40:10 -0600
Message-Id: <20221229184011.62925-1-samuel@sholland.org>
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Precedence: bulk

If there is more than one parent clock in the devicetree, the
driver sets .num_parents to a larger value than the number of array
elements, which causes an out-of-bounds read in the clock framework.

Fix this by coercing the parent count to a Boolean value, like the
driver expects.

Fixes: 3855c2c3e546 ("rtc: sun6i: Expose the 32kHz oscillator")
Signed-off-by: Samuel Holland <samuel@sholland.org>
---

 drivers/rtc/rtc-sun6i.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index ed5516089e9a..a22358a44e32 100644
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -294,7 +294,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node,
 
 	init.parent_names = parents;
 	/* ... number of clock parents will be 1. */
-	init.num_parents = of_clk_get_parent_count(node) + 1;
+	init.num_parents = !!of_clk_get_parent_count(node) + 1;
 	of_property_read_string_index(node, "clock-output-names", 0,
 				      &init.name);
 
-- 
2.37.4