Re: [PATCH] clk: qcom: ipq-cmn-pll: Assign .num before accessing .hws

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 9/5/26 10:48 PM, Aamir Ahmed 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 (UBSAN_BOUNDS)
> 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 ipq_cmn_pll_register_clks() due to .num being assigned
> only after the fixed rate output clocks and the CMN PLL clock have been
> stored in .hws[]. If registering one of the fixed rate clocks fails, the
> unwind loop under unregister_fixed_clk reads .hws[] while .num is still
> zero as well. With CONFIG_UBSAN_BOUNDS and a compiler that implements
> __counted_by (GCC 15.1+ or Clang 20.1+), this triggers an
> array-index-out-of-bounds report during probe, and with
> CONFIG_UBSAN_TRAP the first store traps so the CMN PLL clocks are never
> provided.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad