clk: bcm: rpi: Prevent out-of-bounds access

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@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/20220713154953.3336-2-stefan.wahren@i2se.com
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Ivan T. Ivanov <iivanov@suse.de>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index 39d63c983d62cc48eb4443a7c378f3ff3b89db0f..e495f5f382ab9d571a1754bfa56dcf5cc819141e 100644 (file)
--- a/drivers/clk/bcm/clk-raspberrypi.c
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -344,8 +344,13 @@ 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;