`struct clk_hw_onecell_data` is a flexible structure, which means that
it contains flexible-array member at the bottom, in this case array
`hws`:
include/linux/clk-provider.h:
1380 struct clk_hw_onecell_data {
1381 unsigned int num;
1382 struct clk_hw *hws[] __counted_by(num);
1383 };
This could potentially lead to an overwrite of the objects following
`clk_data` in `struct stratix10_clock_data`, in this case
`void __iomem *base;` at run-time:
drivers/clk/socfpga/stratix10-clk.h:
9 struct stratix10_clock_data {
10 struct clk_hw_onecell_data clk_data;
11 void __iomem *base;
12 };
There are currently three different places where memory is allocated for
`struct stratix10_clock_data`, including the flex-array `hws` in
`struct clk_hw_onecell_data`:
drivers/clk/socfpga/clk-agilex.c:
469 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
470 num_clks), GFP_KERNEL);
drivers/clk/socfpga/clk-agilex.c:
509 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
510 num_clks), GFP_KERNEL);
drivers/clk/socfpga/clk-s10.c:
400 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
401 num_clks), GFP_KERNEL);
I'll use just one of them to describe the issue. See below.
Notice that a total of 440 bytes are allocated for flexible-array member
`hws` at line 469:
include/dt-bindings/clock/agilex-clock.h:
70 #define AGILEX_NUM_CLKS 55
drivers/clk/socfpga/clk-agilex.c:
459 struct stratix10_clock_data *clk_data;
460 void __iomem *base;
...
466
467 num_clks = AGILEX_NUM_CLKS;
468
469 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
470 num_clks), GFP_KERNEL);
`struct_size(clk_data, clk_data.hws, num_clks)` above translates to
sizeof(struct stratix10_clock_data) + sizeof(struct clk_hw *) * 55 ==
16 + 8 * 55 == 16 + 440
^^^
|
allocated bytes for flex-array `hws`
474 for (i = 0; i < num_clks; i++)
475 clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
476
477 clk_data->base = base;
and then some data is written into both `hws` and `base` objects.
Fix this by placing the declaration of object `clk_data` at the end of
`struct stratix10_clock_data`. Also, add a comment to make it clear
that this object must always be last in the structure.
Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/clk/socfpga/stratix10-clk.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/socfpga/stratix10-clk.h b/drivers/clk/socfpga/stratix10-clk.h
index 75234e0783e1..83fe4eb3133c 100644
--- a/drivers/clk/socfpga/stratix10-clk.h
+++ b/drivers/clk/socfpga/stratix10-clk.h
@@ -7,8 +7,10 @@
#define __STRATIX10_CLK_H
struct stratix10_clock_data {
- struct clk_hw_onecell_data clk_data;
void __iomem *base;
+
+ /* Must be last */
+ struct clk_hw_onecell_data clk_data;
};
struct stratix10_pll_clock {
--
2.34.1On Wed, Oct 11, 2023 at 03:34:03PM -0600, Gustavo A. R. Silva wrote:
> `struct clk_hw_onecell_data` is a flexible structure, which means that
> it contains flexible-array member at the bottom, in this case array
> `hws`:
>
> include/linux/clk-provider.h:
> 1380 struct clk_hw_onecell_data {
> 1381 unsigned int num;
> 1382 struct clk_hw *hws[] __counted_by(num);
> 1383 };
>
> This could potentially lead to an overwrite of the objects following
> `clk_data` in `struct stratix10_clock_data`, in this case
> `void __iomem *base;` at run-time:
>
> drivers/clk/socfpga/stratix10-clk.h:
> 9 struct stratix10_clock_data {
> 10 struct clk_hw_onecell_data clk_data;
> 11 void __iomem *base;
> 12 };
>
> There are currently three different places where memory is allocated for
> `struct stratix10_clock_data`, including the flex-array `hws` in
> `struct clk_hw_onecell_data`:
>
> drivers/clk/socfpga/clk-agilex.c:
> 469 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
> 470 num_clks), GFP_KERNEL);
>
> drivers/clk/socfpga/clk-agilex.c:
> 509 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
> 510 num_clks), GFP_KERNEL);
>
> drivers/clk/socfpga/clk-s10.c:
> 400 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
> 401 num_clks), GFP_KERNEL);
>
> I'll use just one of them to describe the issue. See below.
>
> Notice that a total of 440 bytes are allocated for flexible-array member
> `hws` at line 469:
>
> include/dt-bindings/clock/agilex-clock.h:
> 70 #define AGILEX_NUM_CLKS 55
>
> drivers/clk/socfpga/clk-agilex.c:
> 459 struct stratix10_clock_data *clk_data;
> 460 void __iomem *base;
> ...
> 466
> 467 num_clks = AGILEX_NUM_CLKS;
> 468
> 469 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
> 470 num_clks), GFP_KERNEL);
>
> `struct_size(clk_data, clk_data.hws, num_clks)` above translates to
> sizeof(struct stratix10_clock_data) + sizeof(struct clk_hw *) * 55 ==
> 16 + 8 * 55 == 16 + 440
> ^^^
> |
> allocated bytes for flex-array `hws`
>
> 474 for (i = 0; i < num_clks; i++)
> 475 clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
> 476
> 477 clk_data->base = base;
>
> and then some data is written into both `hws` and `base` objects.
>
> Fix this by placing the declaration of object `clk_data` at the end of
> `struct stratix10_clock_data`. Also, add a comment to make it clear
> that this object must always be last in the structure.
>
> Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Nice find!
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
>> Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>
> Nice find!
:D
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
Thanks!
--
Gustavo
© 2016 - 2026 Red Hat, Inc.