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

Commit Message

Nathan Chancellor April 25, 2024, 4:55 p.m. UTC

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: [e-mail]
Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
Signed-off-by: Nathan Chancellor <[e-mail]>
---
 drivers/clk/bcm/clk-raspberrypi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Kees Cook April 25, 2024, 5:15 p.m. UTC | #1

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: [e-mail]
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <[e-mail]>

Looks good; thanks!

Reviewed-by: Kees Cook <[e-mail]>

Florian Fainelli April 25, 2024, 9:26 p.m. UTC | #2

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: [e-mail]
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <[e-mail]>

Reviewed-by: Florian Fainelli <[e-mail]>

Stephen Boyd April 30, 2024, 12:04 a.m. UTC | #3

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: [e-mail]
> Fixes: f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
> Signed-off-by: Nathan Chancellor <[e-mail]>
> ---

Applied to clk-next

Patch

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++;