[PATCH] clk: rs9: Reserve 8 struct clk_hw slots for for 9FGV0841

[PATCH] clk: rs9: Reserve 8 struct clk_hw slots for for 9FGV0841

[Marek Vasut]

The 9FGV0841 has 8 outputs and registers 8 struct clk_hw, make sure
there are 8 slots for those newly registered clk_hw pointers, else
there is going to be out of bounds write when pointers 4..7 are set
into struct rs9_driver_data .clk_dif[4..7] field.

Since there are other structure members past this struct clk_hw
pointer array, writing to .clk_dif[4..7] fields only corrupts the
struct rs9_driver_data content, without crashing the kernel. However,
the kernel does crash when the driver is unbound or during suspend.

Fix this, increase the struct clk_hw pointer array size to the
maximum output count of 9FGV0841, which is the biggest chip that
is supported by this driver.

Cc: stable@vger.kernel.org
Fixes: f0e5e1800204 ("clk: rs9: Add support for 9FGV0841")
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
---
 drivers/clk/clk-renesas-pcie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-renesas-pcie.c b/drivers/clk/clk-renesas-pcie.c
index 4c3a5e4eb77ac..f94a9c4d0b670 100644
--- a/drivers/clk/clk-renesas-pcie.c
+++ b/drivers/clk/clk-renesas-pcie.c
@@ -64,7 +64,7 @@ struct rs9_driver_data {
 	struct i2c_client	*client;
 	struct regmap		*regmap;
 	const struct rs9_chip_info *chip_info;
-	struct clk_hw		*clk_dif[4];
+	struct clk_hw		*clk_dif[8];
 	u8			pll_amplitude;
 	u8			pll_ssc;
 	u8			clk_dif_sr;
-- 
2.51.0

Re: [PATCH] clk: rs9: Reserve 8 struct clk_hw slots for for 9FGV0841

[Geert Uytterhoeven]

Hi Marek,

On Sun, 18 Jan 2026 at 03:58, Marek Vasut
<marek.vasut+renesas@mailbox.org> wrote:
> The 9FGV0841 has 8 outputs and registers 8 struct clk_hw, make sure
> there are 8 slots for those newly registered clk_hw pointers, else
> there is going to be out of bounds write when pointers 4..7 are set
> into struct rs9_driver_data .clk_dif[4..7] field.
>
> Since there are other structure members past this struct clk_hw
> pointer array, writing to .clk_dif[4..7] fields only corrupts the
> struct rs9_driver_data content, without crashing the kernel. However,

I am not sure that is true. As the last 3 fields are just bytes, up to 3
pointers may be written outside the structure, which is 32 or 64 bytes large.
So any buffer overflow may corrupt another object from the 32-byte or
64-byte slab.

> the kernel does crash when the driver is unbound or during suspend.
>
> Fix this, increase the struct clk_hw pointer array size to the
> maximum output count of 9FGV0841, which is the biggest chip that
> is supported by this driver.
>
> Cc: stable@vger.kernel.org
> Fixes: f0e5e1800204 ("clk: rs9: Add support for 9FGV0841")
> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

The crash I saw is gone, so:
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] clk: rs9: Reserve 8 struct clk_hw slots for for 9FGV0841

[Marek Vasut]

On 1/19/26 2:55 PM, Geert Uytterhoeven wrote:

Hello Geert,

> On Sun, 18 Jan 2026 at 03:58, Marek Vasut
> <marek.vasut+renesas@mailbox.org> wrote:
>> The 9FGV0841 has 8 outputs and registers 8 struct clk_hw, make sure
>> there are 8 slots for those newly registered clk_hw pointers, else
>> there is going to be out of bounds write when pointers 4..7 are set
>> into struct rs9_driver_data .clk_dif[4..7] field.
>>
>> Since there are other structure members past this struct clk_hw
>> pointer array, writing to .clk_dif[4..7] fields only corrupts the
>> struct rs9_driver_data content, without crashing the kernel. However,
> 
> I am not sure that is true. As the last 3 fields are just bytes, up to 3
> pointers may be written outside the structure, which is 32 or 64 bytes large.
> So any buffer overflow may corrupt another object from the 32-byte or
> 64-byte slab.
Indeed, updated in V2, thanks.