[PATCH] ep93xx: clock: Fix UAF in ep93xx_clk_register_gate()

[PATCH] ep93xx: clock: Fix UAF in ep93xx_clk_register_gate()

[Alexander Sverdlin]

arch/arm/mach-ep93xx/clock.c:151:2: note: Taking true branch
if (IS_ERR(clk))
^
arch/arm/mach-ep93xx/clock.c:152:3: note: Memory is released
kfree(psc);
^~~~~~~~~~
arch/arm/mach-ep93xx/clock.c:154:2: note: Use of memory after it is freed
return &psc->hw;
^ ~~~~~~~~

Link: https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/B5YCO2NJEXINCYE26Y255LCVMO55BGWW/
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 9645ccc7bd7a ("ep93xx: clock: convert in-place to COMMON_CLK")
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 arch/arm/mach-ep93xx/clock.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
index cc75087134d3..4aee14f18123 100644
--- a/arch/arm/mach-ep93xx/clock.c
+++ b/arch/arm/mach-ep93xx/clock.c
@@ -148,8 +148,10 @@ static struct clk_hw *ep93xx_clk_register_gate(const char *name,
 	psc->lock = &clk_lock;
 
 	clk = clk_register(NULL, &psc->hw);
-	if (IS_ERR(clk))
+	if (IS_ERR(clk)) {
 		kfree(psc);
+		return (void *)clk;
+	}
 
 	return &psc->hw;
 }
-- 
2.34.1

[PATCH] ep93xx: clock: Don't use plain integer as NULL pointer

[Alexander Sverdlin]

Fix sparse warning:
arch/arm/mach-ep93xx/clock.c:210:35: sparse: sparse: Using plain integer as NULL pointer

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/TLFJ6D7WGMDJSQ6XK7UZE4XR2PLRZJSV/
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 arch/arm/mach-ep93xx/clock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
index 4aee14f18123..71c54da0c1e1 100644
--- a/arch/arm/mach-ep93xx/clock.c
+++ b/arch/arm/mach-ep93xx/clock.c
@@ -209,7 +209,7 @@ static int ep93xx_mux_determine_rate(struct clk_hw *hw,
 				struct clk_rate_request *req)
 {
 	unsigned long rate = req->rate;
-	struct clk *best_parent = 0;
+	struct clk *best_parent = NULL;
 	unsigned long __parent_rate;
 	unsigned long best_rate = 0, actual_rate, mclk_rate;
 	unsigned long best_parent_rate;
-- 
2.34.1

Re: [PATCH] ep93xx: clock: Fix UAF in ep93xx_clk_register_gate()

[Nick Desaulniers]

On Thu, Jan 20, 2022 at 02:37:38PM +0100, Alexander Sverdlin wrote:
> arch/arm/mach-ep93xx/clock.c:151:2: note: Taking true branch
> if (IS_ERR(clk))
> ^
> arch/arm/mach-ep93xx/clock.c:152:3: note: Memory is released
> kfree(psc);
> ^~~~~~~~~~
> arch/arm/mach-ep93xx/clock.c:154:2: note: Use of memory after it is freed
> return &psc->hw;
> ^ ~~~~~~~~
> 
> Link: https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/B5YCO2NJEXINCYE26Y255LCVMO55BGWW/
> Reported-by: kernel test robot <lkp@intel.com>
> Fixes: 9645ccc7bd7a ("ep93xx: clock: convert in-place to COMMON_CLK")
> Cc: stable@vger.kernel.org
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
> ---
>  arch/arm/mach-ep93xx/clock.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
> index cc75087134d3..4aee14f18123 100644
> --- a/arch/arm/mach-ep93xx/clock.c
> +++ b/arch/arm/mach-ep93xx/clock.c
> @@ -148,8 +148,10 @@ static struct clk_hw *ep93xx_clk_register_gate(const char *name,
>  	psc->lock = &clk_lock;
>  
>  	clk = clk_register(NULL, &psc->hw);
> -	if (IS_ERR(clk))
> +	if (IS_ERR(clk)) {
>  		kfree(psc);
> +		return (void *)clk;

Prefer ERR_CAST to the raw cast. I think that's nicer when we're already
using the IS_ERR macros.

> +	}
>  
>  	return &psc->hw;
>  }
> -- 
> 2.34.1
> 

Re: [PATCH] ep93xx: clock: Fix UAF in ep93xx_clk_register_gate()

[Nick Desaulniers]

On Tue, Jan 25, 2022 at 1:10 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Jan 20, 2022 at 02:37:38PM +0100, Alexander Sverdlin wrote:

Also, consider adding the first line of the warning to your commit
message, please:
arch/arm/mach-ep93xx/clock.c:154:2: warning: Use of memory after it is
freed [clang-analyzer-unix.Malloc]

> > arch/arm/mach-ep93xx/clock.c:151:2: note: Taking true branch
> > if (IS_ERR(clk))
> > ^
> > arch/arm/mach-ep93xx/clock.c:152:3: note: Memory is released
> > kfree(psc);
> > ^~~~~~~~~~
> > arch/arm/mach-ep93xx/clock.c:154:2: note: Use of memory after it is freed
> > return &psc->hw;
> > ^ ~~~~~~~~
> >
> > Link: https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/B5YCO2NJEXINCYE26Y255LCVMO55BGWW/
> > Reported-by: kernel test robot <lkp@intel.com>
> > Fixes: 9645ccc7bd7a ("ep93xx: clock: convert in-place to COMMON_CLK")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
> > ---
> >  arch/arm/mach-ep93xx/clock.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
> > index cc75087134d3..4aee14f18123 100644
> > --- a/arch/arm/mach-ep93xx/clock.c
> > +++ b/arch/arm/mach-ep93xx/clock.c
> > @@ -148,8 +148,10 @@ static struct clk_hw *ep93xx_clk_register_gate(const char *name,
> >       psc->lock = &clk_lock;
> >
> >       clk = clk_register(NULL, &psc->hw);
> > -     if (IS_ERR(clk))
> > +     if (IS_ERR(clk)) {
> >               kfree(psc);
> > +             return (void *)clk;
>
> Prefer ERR_CAST to the raw cast. I think that's nicer when we're already
> using the IS_ERR macros.
>
> > +     }
> >
> >       return &psc->hw;
> >  }
> > --
> > 2.34.1
> >



-- 
Thanks,
~Nick Desaulniers