From: Kees Cook <keescook@xxxxxxxxxxxx> [ Upstream commit 21b8a1dd56a163825e5749b303858fb902ebf198 ] With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. msc313_rtc_probe() was passing clk_disable_unprepare() directly, which did not have matching prototypes for devm_add_action_or_reset()'s callback argument. Refactor to use devm_clk_get_enabled() instead. This was found as a result of Clang's new -Wcast-function-type-strict flag, which is more sensitive than the simpler -Wcast-function-type, which only checks for type width mismatches. Reported-by: kernel test robot <lkp@xxxxxxxxx> Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@xxxxxxxxx Suggested-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> Cc: Daniel Palmer <daniel@xxxxxxxxx> Cc: Romain Perier <romain.perier@xxxxxxxxx> Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx> Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Cc: linux-rtc@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Daniel Palmer <daniel@xxxxxxxxx> Tested-by: Daniel Palmer <daniel@xxxxxxxxx> Link: https://lore.kernel.org/r/20221202184525.gonna.423-kees@xxxxxxxxxx Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/rtc/rtc-msc313.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c index f3fde013c4b8..8d7737e0e2e0 100644 --- a/drivers/rtc/rtc-msc313.c +++ b/drivers/rtc/rtc-msc313.c @@ -212,22 +212,12 @@ static int msc313_rtc_probe(struct platform_device *pdev) return ret; } - clk = devm_clk_get(dev, NULL); + clk = devm_clk_get_enabled(dev, NULL); if (IS_ERR(clk)) { dev_err(dev, "No input reference clock\n"); return PTR_ERR(clk); } - ret = clk_prepare_enable(clk); - if (ret) { - dev_err(dev, "Failed to enable the reference clock, %d\n", ret); - return ret; - } - - ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk); - if (ret) - return ret; - rate = clk_get_rate(clk); writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L); writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H); -- 2.35.1
