* [PATCH v3 1/2][next] clk: socfpga: Fix undefined behavior bug in struct stratix10_clock_data
2023-10-24 3:30 [PATCH v3 0/2][next] clk: socfpga: Fix undefined behavior bug and add bounds-checking coverage Gustavo A. R. Silva
@ 2023-10-24 3:30 ` Gustavo A. R. Silva
2023-10-24 3:31 ` [PATCH v3 2/2][next] clk: socfpga: agilex: Add bounds-checking coverage for " Gustavo A. R. Silva
1 sibling, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2023-10-24 3:30 UTC (permalink / raw)
To: Dinh Nguyen, Michael Turquette, Stephen Boyd
Cc: Kees Cook, linux-kernel, Gustavo A. R. Silva, linux-hardening,
linux-clk
`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.
-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.
Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw")
Cc: stable@vger.kernel.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
Changes in v3:
- None, really. Just Cc linux-clk@vger.kernel.org this time.
Changes in v2:
- Mention -Wflex-array-member-not-at-end in the changelog text.
- Link: https://lore.kernel.org/linux-hardening/bb2ae50abf622d4b6fda1a326ce830627356ab7c.1697493574.git.gustavoars@kernel.org/
v1:
- Link: https://lore.kernel.org/linux-hardening/5dd8483177dc8cd91d021170b6717f2e570bab03.1697059539.git.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 {
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v3 2/2][next] clk: socfpga: agilex: Add bounds-checking coverage for struct stratix10_clock_data
2023-10-24 3:30 [PATCH v3 0/2][next] clk: socfpga: Fix undefined behavior bug and add bounds-checking coverage Gustavo A. R. Silva
2023-10-24 3:30 ` [PATCH v3 1/2][next] clk: socfpga: Fix undefined behavior bug in struct stratix10_clock_data Gustavo A. R. Silva
@ 2023-10-24 3:31 ` Gustavo A. R. Silva
1 sibling, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2023-10-24 3:31 UTC (permalink / raw)
To: Dinh Nguyen, Michael Turquette, Stephen Boyd
Cc: Kees Cook, linux-kernel, Gustavo A. R. Silva, linux-hardening,
linux-clk
In order to gain the bounds-checking coverage that __counted_by provides
to flexible-array members at run-time via CONFIG_UBSAN_BOUNDS (for array
indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions),
we must make sure that the counter member, in this case `num`, is updated
before the first access to the flex-array member, in this case array `hws`.
commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") introduced `__counted_by` for `struct clk_hw_onecell_data`
together with changes to relocate some of assignments of counter `num`
before `hws` is accessed:
include/linux/clk-provider.h:
1380 struct clk_hw_onecell_data {
1381 unsigned int num;
1382 struct clk_hw *hws[] __counted_by(num);
1383 };
However, this structure is used as a member in other structs, in this
case in `struct sstratix10_clock_data`:
drivers/clk/socfpga/stratix10-clk.h:
9 struct stratix10_clock_data {
10 void __iomem *base;
11
12 /* Must be last */
13 struct clk_hw_onecell_data clk_data;
14 };
Hence, we need to move the assignments to `clk_data->clk_data.num` after
allocations for `struct stratix10_clock_data` and before accessing the
flexible array `clk_data->clk_data.hws`. And, as assignments for both
`clk_data->clk_data.num` and `clk_data->base` are originally adjacent to
each other, relocate both assignments together.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
Changes in v3:
- None, really. Just Cc linux-clk@vger.kernel.org this time.
Changes in v2:
- None.
- Link: https://lore.kernel.org/linux-hardening/f531ae35ef434b62f48534c67ad3b1013bff0536.1697493574.git.gustavoars@kernel.org/
v1:
- Link: https://lore.kernel.org/linux-hardening/fd4cd8503316d536e1a84fa2ae5bdefdd4b24afe.1697059539.git.gustavoars@kernel.org/
drivers/clk/socfpga/clk-agilex.c | 12 ++++++------
drivers/clk/socfpga/clk-s10.c | 6 +++---
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/clk/socfpga/clk-agilex.c b/drivers/clk/socfpga/clk-agilex.c
index 6b65a74aefa6..8dd94f64756b 100644
--- a/drivers/clk/socfpga/clk-agilex.c
+++ b/drivers/clk/socfpga/clk-agilex.c
@@ -471,12 +471,12 @@ static int agilex_clkmgr_init(struct platform_device *pdev)
if (!clk_data)
return -ENOMEM;
+ clk_data->clk_data.num = num_clks;
+ clk_data->base = base;
+
for (i = 0; i < num_clks; i++)
clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
- clk_data->base = base;
- clk_data->clk_data.num = num_clks;
-
agilex_clk_register_pll(agilex_pll_clks, ARRAY_SIZE(agilex_pll_clks), clk_data);
agilex_clk_register_c_perip(agilex_main_perip_c_clks,
@@ -511,12 +511,12 @@ static int n5x_clkmgr_init(struct platform_device *pdev)
if (!clk_data)
return -ENOMEM;
- for (i = 0; i < num_clks; i++)
- clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
-
clk_data->base = base;
clk_data->clk_data.num = num_clks;
+ for (i = 0; i < num_clks; i++)
+ clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
+
n5x_clk_register_pll(agilex_pll_clks, ARRAY_SIZE(agilex_pll_clks), clk_data);
n5x_clk_register_c_perip(n5x_main_perip_c_clks,
diff --git a/drivers/clk/socfpga/clk-s10.c b/drivers/clk/socfpga/clk-s10.c
index 3752bd9c103c..b4bf4e2d38e1 100644
--- a/drivers/clk/socfpga/clk-s10.c
+++ b/drivers/clk/socfpga/clk-s10.c
@@ -402,12 +402,12 @@ static int s10_clkmgr_init(struct platform_device *pdev)
if (!clk_data)
return -ENOMEM;
- for (i = 0; i < num_clks; i++)
- clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
-
clk_data->base = base;
clk_data->clk_data.num = num_clks;
+ for (i = 0; i < num_clks; i++)
+ clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
+
s10_clk_register_pll(s10_pll_clks, ARRAY_SIZE(s10_pll_clks), clk_data);
s10_clk_register_c_perip(s10_main_perip_c_clks,
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread