* [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() @ 2022-11-18 23:31 Kees Cook 2022-11-19 8:05 ` Christophe JAILLET 0 siblings, 1 reply; 4+ messages in thread From: Kees Cook @ 2022-11-18 23:31 UTC (permalink / raw) To: Daniel Palmer Cc: Kees Cook, kernel test robot, Romain Perier, Alessandro Zummo, Alexandre Belloni, Gustavo A. R. Silva, linux-arm-kernel, linux-rtc, Nathan Chancellor, Nick Desaulniers, Tom Rix, linux-kernel, llvm, linux-hardening 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. Add a wrapper and remove the cast. 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@intel.com> Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com Cc: Daniel Palmer <daniel@thingy.jp> Cc: Romain Perier <romain.perier@gmail.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-rtc@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/rtc/rtc-msc313.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c index f3fde013c4b8..36e3e77f303e 100644 --- a/drivers/rtc/rtc-msc313.c +++ b/drivers/rtc/rtc-msc313.c @@ -177,6 +177,13 @@ static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id) return IRQ_HANDLED; } +static void msc313_clk_disable_unprepare(void *data) +{ + struct clk *clk = data; + + clk_disable_unprepare(clk); +} + static int msc313_rtc_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; @@ -224,7 +231,7 @@ static int msc313_rtc_probe(struct platform_device *pdev) return ret; } - ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk); + ret = devm_add_action_or_reset(dev, msc313_clk_disable_unprepare, clk); if (ret) return ret; -- 2.34.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() 2022-11-18 23:31 [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() Kees Cook @ 2022-11-19 8:05 ` Christophe JAILLET 2022-12-02 4:46 ` Kees Cook 0 siblings, 1 reply; 4+ messages in thread From: Christophe JAILLET @ 2022-11-19 8:05 UTC (permalink / raw) To: Kees Cook, Daniel Palmer Cc: kernel test robot, Romain Perier, Alessandro Zummo, Alexandre Belloni, Gustavo A. R. Silva, linux-arm-kernel, linux-rtc, Nathan Chancellor, Nick Desaulniers, Tom Rix, linux-kernel, llvm, linux-hardening Le 19/11/2022 à 00:31, Kees Cook a écrit : > 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. Add a wrapper and remove the cast. > > 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@intel.com> > Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com > Cc: Daniel Palmer <daniel@thingy.jp> > Cc: Romain Perier <romain.perier@gmail.com> > Cc: Alessandro Zummo <a.zummo@towertech.it> > Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-rtc@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > drivers/rtc/rtc-msc313.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c > index f3fde013c4b8..36e3e77f303e 100644 > --- a/drivers/rtc/rtc-msc313.c > +++ b/drivers/rtc/rtc-msc313.c > @@ -177,6 +177,13 @@ static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id) > return IRQ_HANDLED; > } > > +static void msc313_clk_disable_unprepare(void *data) > +{ > + struct clk *clk = data; > + > + clk_disable_unprepare(clk); > +} > + > static int msc313_rtc_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > @@ -224,7 +231,7 @@ static int msc313_rtc_probe(struct platform_device *pdev) > return ret; > } > > - ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk); > + ret = devm_add_action_or_reset(dev, msc313_clk_disable_unprepare, clk); > if (ret) > return ret; > Hi, another way to fix it, is to use devm_clk_get_enabled(). It removes some LoC instead of introducing some new ones and saves a few bytes of memory. CJ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() 2022-11-19 8:05 ` Christophe JAILLET @ 2022-12-02 4:46 ` Kees Cook 2022-12-02 17:54 ` Christophe JAILLET 0 siblings, 1 reply; 4+ messages in thread From: Kees Cook @ 2022-12-02 4:46 UTC (permalink / raw) To: Christophe JAILLET Cc: Daniel Palmer, kernel test robot, Romain Perier, Alessandro Zummo, Alexandre Belloni, Gustavo A. R. Silva, linux-arm-kernel, linux-rtc, Nathan Chancellor, Nick Desaulniers, Tom Rix, linux-kernel, llvm, linux-hardening On Sat, Nov 19, 2022 at 09:05:28AM +0100, Christophe JAILLET wrote: > Le 19/11/2022 à 00:31, Kees Cook a écrit : > > 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. Add a wrapper and remove the cast. > > > > 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@intel.com> > > Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com > > Cc: Daniel Palmer <daniel@thingy.jp> > > Cc: Romain Perier <romain.perier@gmail.com> > > Cc: Alessandro Zummo <a.zummo@towertech.it> > > Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> > > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > > Cc: linux-arm-kernel@lists.infradead.org > > Cc: linux-rtc@vger.kernel.org > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > drivers/rtc/rtc-msc313.c | 9 ++++++++- > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c > > index f3fde013c4b8..36e3e77f303e 100644 > > --- a/drivers/rtc/rtc-msc313.c > > +++ b/drivers/rtc/rtc-msc313.c > > @@ -177,6 +177,13 @@ static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id) > > return IRQ_HANDLED; > > } > > +static void msc313_clk_disable_unprepare(void *data) > > +{ > > + struct clk *clk = data; > > + > > + clk_disable_unprepare(clk); > > +} > > + > > static int msc313_rtc_probe(struct platform_device *pdev) > > { > > struct device *dev = &pdev->dev; > > @@ -224,7 +231,7 @@ static int msc313_rtc_probe(struct platform_device *pdev) > > return ret; > > } > > - ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk); > > + ret = devm_add_action_or_reset(dev, msc313_clk_disable_unprepare, clk); > > if (ret) > > return ret; > > Hi, > > another way to fix it, is to use devm_clk_get_enabled(). > > It removes some LoC instead of introducing some new ones and saves a few > bytes of memory. Hrm, I'm not familiar with the clk stuff here -- how do I use it? Should it just be like this? (The NULL argument is ok?) 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); -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() 2022-12-02 4:46 ` Kees Cook @ 2022-12-02 17:54 ` Christophe JAILLET 0 siblings, 0 replies; 4+ messages in thread From: Christophe JAILLET @ 2022-12-02 17:54 UTC (permalink / raw) To: Kees Cook Cc: Daniel Palmer, kernel test robot, Romain Perier, Alessandro Zummo, Alexandre Belloni, Gustavo A. R. Silva, linux-arm-kernel, linux-rtc, Nathan Chancellor, Nick Desaulniers, Tom Rix, linux-kernel, llvm, linux-hardening Le 02/12/2022 à 05:46, Kees Cook a écrit : > On Sat, Nov 19, 2022 at 09:05:28AM +0100, Christophe JAILLET wrote: >> Le 19/11/2022 à 00:31, Kees Cook a écrit : >>> 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. Add a wrapper and remove the cast. >>> >>> 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@intel.com> >>> Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com >>> Cc: Daniel Palmer <daniel@thingy.jp> >>> Cc: Romain Perier <romain.perier@gmail.com> >>> Cc: Alessandro Zummo <a.zummo@towertech.it> >>> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> >>> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> >>> Cc: linux-arm-kernel@lists.infradead.org >>> Cc: linux-rtc@vger.kernel.org >>> Signed-off-by: Kees Cook <keescook@chromium.org> >>> --- >>> drivers/rtc/rtc-msc313.c | 9 ++++++++- >>> 1 file changed, 8 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c >>> index f3fde013c4b8..36e3e77f303e 100644 >>> --- a/drivers/rtc/rtc-msc313.c >>> +++ b/drivers/rtc/rtc-msc313.c >>> @@ -177,6 +177,13 @@ static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id) >>> return IRQ_HANDLED; >>> } >>> +static void msc313_clk_disable_unprepare(void *data) >>> +{ >>> + struct clk *clk = data; >>> + >>> + clk_disable_unprepare(clk); >>> +} >>> + >>> static int msc313_rtc_probe(struct platform_device *pdev) >>> { >>> struct device *dev = &pdev->dev; >>> @@ -224,7 +231,7 @@ static int msc313_rtc_probe(struct platform_device *pdev) >>> return ret; >>> } >>> - ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk); >>> + ret = devm_add_action_or_reset(dev, msc313_clk_disable_unprepare, clk); >>> if (ret) >>> return ret; >> >> Hi, >> >> another way to fix it, is to use devm_clk_get_enabled(). >> >> It removes some LoC instead of introducing some new ones and saves a few >> bytes of memory. > > Hrm, I'm not familiar with the clk stuff here -- how do I use it? Should > it just be like this? (The NULL argument is ok?) Yes, the code below looks fine. NULL argument is ok. See [1]. Both function are very similar. devm_clk_get_enabled() just pass some additional init() and exit() functions. CJ [1]: https://elixir.bootlin.com/linux/v6.1-rc7/source/drivers/clk/clk-devres.c#L63 > > 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); > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-12-02 17:55 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2022-11-18 23:31 [PATCH] rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() Kees Cook 2022-11-19 8:05 ` Christophe JAILLET 2022-12-02 4:46 ` Kees Cook 2022-12-02 17:54 ` Christophe JAILLET
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