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

BugLink: https://bugs.launchpad.net/bugs/1991840
[ 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@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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index 97612860ce0e10cec53a8720b10ebb86588c7ce1..834bcc256e921069771714f100372e4b2d7a91f0 100644 (file)
--- 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;