[PATCH 0/2] clk: bcm: Move a couple of __counted_by initializations

[PATCH 0/2] clk: bcm: Move a couple of __counted_by initializations

[Nathan Chancellor]

Hi all,

This series addresses two UBSAN warnings I see on my Raspberry Pi 4 with
recent releases of clang that support __counted_by by moving the
initializations of the element count member before any accesses of the
flexible array member.

I marked these for stable because more distributions are enabling the
bounds sanitizer [1][2], so the warnings will show up when the kernel is
built with a compiler that supports __counted_by, so it seems worth
fixing this for future users.

[1]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1914685
[2]: https://src.fedoraproject.org/rpms/kernel/c/79a2207963b8fea452acfc5dea13ed54bd36c7e1

---
Nathan Chancellor (2):
      clk: bcm: dvp: Assign ->num before accessing ->hws
      clk: bcm: rpi: Assign ->num before accessing ->hws

 drivers/clk/bcm/clk-bcm2711-dvp.c | 3 ++-
 drivers/clk/bcm/clk-raspberrypi.c | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)
---
base-commit: ed30a4a51bb196781c8058073ea720133a65596f
change-id: 20240424-cbl-bcm-assign-counted-by-val-before-access-cf19d630f2b4

Best regards,
-- 
Nathan Chancellor <nathan@kernel.org>

[PATCH 1/2] clk: bcm: dvp: Assign ->num before accessing ->hws

[Nathan Chancellor]

Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
with __counted_by, which informs the bounds sanitizer about the number
of elements in hws, so that it can warn when hws is accessed out of
bounds. As noted in that change, the __counted_by member must be
initialized with the number of elements before the first array access
happens, otherwise there will be a warning from each access prior to the
initialization because the number of elements is zero. This occurs in
clk_dvp_probe() due to ->num being assigned after ->hws has been
accessed:

  UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-bcm2711-dvp.c:59:2
  index 0 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')

Move the ->num initialization to before the first access of ->hws, which
clears up the warning.

Cc: stable@vger.kernel.org
Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/clk/bcm/clk-bcm2711-dvp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-bcm2711-dvp.c b/drivers/clk/bcm/clk-bcm2711-dvp.c
index e4fbbf3c40fe..3cb235df9d37 100644
--- a/drivers/clk/bcm/clk-bcm2711-dvp.c
+++ b/drivers/clk/bcm/clk-bcm2711-dvp.c
@@ -56,6 +56,8 @@ static int clk_dvp_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	data->num = NR_CLOCKS;
+
 	data->hws[0] = clk_hw_register_gate_parent_data(&pdev->dev,
 							"hdmi0-108MHz",
 							&clk_dvp_parent, 0,
@@ -76,7 +78,6 @@ static int clk_dvp_probe(struct platform_device *pdev)
 		goto unregister_clk0;
 	}
 
-	data->num = NR_CLOCKS;
 	ret = of_clk_add_hw_provider(pdev->dev.of_node, of_clk_hw_onecell_get,
 				     data);
 	if (ret)

-- 
2.44.0

Re: [PATCH 1/2] clk: bcm: dvp: Assign ->num before accessing ->hws

[Kees Cook]

On Thu, Apr 25, 2024 at 09:55:51AM -0700, Nathan Chancellor wrote:
> Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
> __counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
> with __counted_by, which informs the bounds sanitizer about the number
> of elements in hws, so that it can warn when hws is accessed out of
> bounds. As noted in that change, the __counted_by member must be
> initialized with the number of elements before the first array access
> happens, otherwise there will be a warning from each access prior to the
> initialization because the number of elements is zero. This occurs in
> clk_dvp_probe() due to ->num being assigned after ->hws has been
> accessed:
> 
>   UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-bcm2711-dvp.c:59:2
>   index 0 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> Move the ->num initialization to before the first access of ->hws, which
> clears up the warning.
> 
> Cc: stable@vger.kernel.org
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Thanks for finding this!

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH 1/2] clk: bcm: dvp: Assign ->num before accessing ->hws

[Florian Fainelli]

[-- Attachment #1: Type: text/plain, Size: 1231 bytes --]

On 4/25/24 09:55, Nathan Chancellor wrote:
> Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
> __counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
> with __counted_by, which informs the bounds sanitizer about the number
> of elements in hws, so that it can warn when hws is accessed out of
> bounds. As noted in that change, the __counted_by member must be
> initialized with the number of elements before the first array access
> happens, otherwise there will be a warning from each access prior to the
> initialization because the number of elements is zero. This occurs in
> clk_dvp_probe() due to ->num being assigned after ->hws has been
> accessed:
> 
>    UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-bcm2711-dvp.c:59:2
>    index 0 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> Move the ->num initialization to before the first access of ->hws, which
> clears up the warning.
> 
> Cc: stable@vger.kernel.org
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian


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Re: [PATCH 1/2] clk: bcm: dvp: Assign ->num before accessing ->hws

[Stephen Boyd]

Quoting Nathan Chancellor (2024-04-25 09:55:51)
> Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
> __counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
> with __counted_by, which informs the bounds sanitizer about the number
> of elements in hws, so that it can warn when hws is accessed out of
> bounds. As noted in that change, the __counted_by member must be
> initialized with the number of elements before the first array access
> happens, otherwise there will be a warning from each access prior to the
> initialization because the number of elements is zero. This occurs in
> clk_dvp_probe() due to ->num being assigned after ->hws has been
> accessed:
> 
>   UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-bcm2711-dvp.c:59:2
>   index 0 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> Move the ->num initialization to before the first access of ->hws, which
> clears up the warning.
> 
> Cc: stable@vger.kernel.org
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---

Applied to clk-next

[PATCH 2/2] clk: bcm: rpi: Assign ->num before accessing ->hws

[Nathan Chancellor]

Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
with __counted_by, which informs the bounds sanitizer about the number
of elements in hws, so that it can warn when hws is accessed out of
bounds. As noted in that change, the __counted_by member must be
initialized with the number of elements before the first array access
happens, otherwise there will be a warning from each access prior to the
initialization because the number of elements is zero. This occurs in
raspberrypi_discover_clocks() due to ->num being assigned after ->hws
has been accessed:

  UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-raspberrypi.c:374:4
  index 3 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')

Move the ->num initialization to before the first access of ->hws, which
clears up the warning.

Cc: stable@vger.kernel.org
Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/clk/bcm/clk-raspberrypi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index 829406dc44a2..4d411408e4af 100644
--- a/drivers/clk/bcm/clk-raspberrypi.c
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -371,8 +371,8 @@ static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
 			if (IS_ERR(hw))
 				return PTR_ERR(hw);
 
-			data->hws[clks->id] = hw;
 			data->num = clks->id + 1;
+			data->hws[clks->id] = hw;
 		}
 
 		clks++;

-- 
2.44.0

Re: [PATCH 2/2] clk: bcm: rpi: Assign ->num before accessing ->hws

[Kees Cook]

On Thu, Apr 25, 2024 at 09:55:52AM -0700, Nathan Chancellor wrote:
> Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
> __counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
> with __counted_by, which informs the bounds sanitizer about the number
> of elements in hws, so that it can warn when hws is accessed out of
> bounds. As noted in that change, the __counted_by member must be
> initialized with the number of elements before the first array access
> happens, otherwise there will be a warning from each access prior to the
> initialization because the number of elements is zero. This occurs in
> raspberrypi_discover_clocks() due to ->num being assigned after ->hws
> has been accessed:
> 
>   UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-raspberrypi.c:374:4
>   index 3 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> Move the ->num initialization to before the first access of ->hws, which
> clears up the warning.
> 
> Cc: stable@vger.kernel.org
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Looks good; thanks!

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH 2/2] clk: bcm: rpi: Assign ->num before accessing ->hws

[Florian Fainelli]

[-- Attachment #1: Type: text/plain, Size: 1246 bytes --]

On 4/25/24 09:55, Nathan Chancellor wrote:
> Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
> __counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
> with __counted_by, which informs the bounds sanitizer about the number
> of elements in hws, so that it can warn when hws is accessed out of
> bounds. As noted in that change, the __counted_by member must be
> initialized with the number of elements before the first array access
> happens, otherwise there will be a warning from each access prior to the
> initialization because the number of elements is zero. This occurs in
> raspberrypi_discover_clocks() due to ->num being assigned after ->hws
> has been accessed:
> 
>    UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-raspberrypi.c:374:4
>    index 3 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> Move the ->num initialization to before the first access of ->hws, which
> clears up the warning.
> 
> Cc: stable@vger.kernel.org
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian


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Re: [PATCH 2/2] clk: bcm: rpi: Assign ->num before accessing ->hws

[Stephen Boyd]

Quoting Nathan Chancellor (2024-04-25 09:55:52)
> Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
> __counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
> with __counted_by, which informs the bounds sanitizer about the number
> of elements in hws, so that it can warn when hws is accessed out of
> bounds. As noted in that change, the __counted_by member must be
> initialized with the number of elements before the first array access
> happens, otherwise there will be a warning from each access prior to the
> initialization because the number of elements is zero. This occurs in
> raspberrypi_discover_clocks() due to ->num being assigned after ->hws
> has been accessed:
> 
>   UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-raspberrypi.c:374:4
>   index 3 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> Move the ->num initialization to before the first access of ->hws, which
> clears up the warning.
> 
> Cc: stable@vger.kernel.org
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---

Applied to clk-next