linux-kernel - Re: [PATCH] clk: s2mps11: initialise clk_hw_onecell_data::num before accessing ::hws[] in probe()

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Message-ID: <6073eb68-560c-4864-92d7-c6f61b187f6d@kernel.org>
Date: Wed, 26 Mar 2025 15:12:25 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: André Draszik <andre.draszik@...aro.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Kees Cook <kees@...nel.org>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
 linux-clk@...r.kernel.org, linux-hardening@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH] clk: s2mps11: initialise clk_hw_onecell_data::num before
 accessing ::hws[] in probe()

On 26/03/2025 13:08, André Draszik wrote:
> With UBSAN enabled, we're getting the following trace:
> 
>     UBSAN: array-index-out-of-bounds in .../drivers/clk/clk-s2mps11.c:186:3
>     index 0 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')
> 
> This is because commit f316cdff8d67 ("clk: Annotate struct
> clk_hw_onecell_data with __counted_by") annotated the hws member of
> that struct 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 initialised
> with the number of elements before the first array access happens,
> otherwise there will be a warning from each access prior to the
> initialisation because the number of elements is zero. This occurs in
> s2mps11_clk_probe() due to ::num being assigned after ::hws access.
> 
> Move the assignment to satisfy the requirement of assign-before-access.
> 

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

Best regards,
Krzysztof