From 21b8a1dd56a163825e5749b303858fb902ebf198 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 2 Dec 2022 10:45:30 -0800 Subject: [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() 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 Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com Suggested-by: Christophe JAILLET Cc: Daniel Palmer Cc: Romain Perier Cc: Alessandro Zummo Cc: Alexandre Belloni Cc: linux-arm-kernel@lists.infradead.org Cc: linux-rtc@vger.kernel.org Signed-off-by: Kees Cook Reviewed-by: Daniel Palmer Tested-by: Daniel Palmer Link: https://lore.kernel.org/r/20221202184525.gonna.423-kees@kernel.org Signed-off-by: Alexandre Belloni --- 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 f3fde013c4b8b1..8d7737e0e2e02c 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);