linux-kernel - [PATCH 5.15 057/107] clk: bcm: rpi: Prevent out-of-bounds access

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Message-Id: <20220906132824.241960043@linuxfoundation.org>
Date:   Tue,  6 Sep 2022 15:30:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Phil Elwell <phil@...pberrypi.com>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "Ivan T. Ivanov" <iivanov@...e.de>,
        Stephen Boyd <sboyd@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 057/107] clk: bcm: rpi: Prevent out-of-bounds access

From: Stefan Wahren <stefan.wahren@...e.com>

[ Upstream commit bc163555603e4ae9c817675ad80d618a4cdbfa2d ]

The while loop in raspberrypi_discover_clocks() relies on the assumption
that the id of the last clock element is zero. Because this data comes
from the Videocore firmware and it doesn't guarantuee such a behavior
this could lead to out-of-bounds access. So fix this by providing
a sentinel element.

Fixes: 93d2725affd6 ("clk: bcm: rpi: Discover the firmware clocks")
Link: https://github.com/raspberrypi/firmware/issues/1688
Suggested-by: Phil Elwell <phil@...pberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@...e.com>
Link: https://lore.kernel.org/r/20220713154953.3336-2-stefan.wahren@i2se.com
Acked-by: Florian Fainelli <f.fainelli@...il.com>
Reviewed-by: Ivan T. Ivanov <iivanov@...e.de>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/clk/bcm/clk-raspberrypi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index 97612860ce0e1..834bcc256e921 100644
--- a/drivers/clk/bcm/clk-raspberrypi.c
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -251,8 +251,13 @@ static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
 	struct rpi_firmware_get_clocks_response *clks;
 	int ret;
 
+	/*
+	 * The firmware doesn't guarantee that the last element of
+	 * RPI_FIRMWARE_GET_CLOCKS is zeroed. So allocate an additional
+	 * zero element as sentinel.
+	 */
 	clks = devm_kcalloc(rpi->dev,
-			    RPI_FIRMWARE_NUM_CLK_ID, sizeof(*clks),
+			    RPI_FIRMWARE_NUM_CLK_ID + 1, sizeof(*clks),
 			    GFP_KERNEL);
 	if (!clks)
 		return -ENOMEM;
-- 
2.35.1