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rtc: ac100: Assign .num before accessing .hws

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Commit f316cdff8d ("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 ac100_rtc_register_clks() due to .num being assigned only
after every clkout clock has been stored in .hws[]. 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.

Initialize .num with AC100_CLKOUT_NUM, the number of elements .hws[] was
allocated with, right after the allocation. That is the value the loop
counter ends up at on the success path anyway, so the provider's
behaviour is unchanged.

Cc: stable@vger.kernel.org
Fixes: f316cdff8d ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
Assisted-by: LLM
Signed-off-by: Aamir Ahmed <elb12345@hotmail.co.uk>
Reviewed-by: Chen-Yu Tsai <wens@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://patch.msgid.link/AS8P251MB00013E724A77A355668B6CCEC8B42@AS8P251MB0001.EURP251.PROD.OUTLOOK.COM
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Aamir Ahmed 2026-09-05 19:38:08 +01:00 committed by Alexandre Belloni
parent b430d1f6d8
commit 6a4117eee8
1 changed files with 2 additions and 1 deletions
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3
drivers/rtc/rtc-ac100.c
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@ -317,6 +317,8 @@ static int ac100_rtc_register_clks(struct ac100_rtc_dev *chip)
if (!chip->clk_data)
return -ENOMEM;
chip->clk_data->num = AC100_CLKOUT_NUM;
chip->rtc_32k_clk = clk_hw_register_fixed_rate(chip->dev,
AC100_RTC_32K_NAME,
NULL, 0,
@ -360,7 +362,6 @@ static int ac100_rtc_register_clks(struct ac100_rtc_dev *chip)
chip->clk_data->hws[i] = &clk->hw;
}
chip->clk_data->num = i;
ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, chip->clk_data);
if (ret)
goto err_unregister_rtc_32k;