linux-hardening - [PATCH 2/2][next] clk: socfpga: agilex: Add bounds-checking coverage for struct stratix10_clock

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Message-ID: <fd4cd8503316d536e1a84fa2ae5bdefdd4b24afe.1697059539.git.gustavoars@kernel.org>
Date: Wed, 11 Oct 2023 15:35:26 -0600
From: "Gustavo A. R. Silva" <gustavoars@...nel.org>
To: Dinh Nguyen <dinguyen@...nel.org>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>
Cc: Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	linux-hardening@...r.kernel.org
Subject: [PATCH 2/2][next] clk: socfpga: agilex: Add bounds-checking coverage
 for struct stratix10_clock_data

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.

Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.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