[v1,2/2] Mark functions with the __nocapture attribute

Commit Message

Emese Revfy June 28, 2016, 11:36 a.m. UTC

The nocapture gcc attribute can be on functions only.
The attribute takes one or more unsigned integer constants as parameters
that specify the function argument(s) of const char* type to initify.
If the marked argument is a vararg then the plugin initifies
all vararg arguments.

I couldn't test the arm, arm64 and powerpc architectures.

Signed-off-by: Emese Revfy <[e-mail]>
---
 arch/arm/include/asm/string.h     | 10 +++---
 arch/arm64/include/asm/string.h   | 23 ++++++------
 arch/powerpc/include/asm/string.h | 19 +++++-----
 arch/x86/boot/string.h            |  4 +--
 arch/x86/include/asm/string_32.h  | 21 +++++------
 arch/x86/include/asm/string_64.h  | 18 +++++-----
 arch/x86/kernel/hpet.c            |  2 +-
 include/asm-generic/bug.h         |  6 ++--
 include/linux/compiler-gcc.h      | 10 ++++--
 include/linux/compiler.h          |  4 +++
 include/linux/fs.h                |  5 +--
 include/linux/printk.h            |  2 +-
 include/linux/string.h            | 73 ++++++++++++++++++++-------------------
 13 files changed, 107 insertions(+), 90 deletions(-)

Comments

Joe Perches June 28, 2016, 4:43 p.m. UTC | #1

On Tue, 2016-06-28 at 13:36 +0200, Emese Revfy wrote:
> The nocapture gcc attribute can be on functions only.
> The attribute takes one or more unsigned integer constants as parameters
> that specify the function argument(s) of const char* type to initify.

Perhaps this should be const <type>*
> diff --git a/arch/arm/include/asm/string.h b/arch/arm/include/asm/string.h
[]
> @@ -7,19 +7,19 @@
[]
>  #define __HAVE_ARCH_MEMCPY
> -extern void * memcpy(void *, const void *, __kernel_size_t);
> +extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);

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Emese Revfy June 28, 2016, 8:40 p.m. UTC | #2

On Tue, 28 Jun 2016 09:43:31 -0700
Joe Perches <[e-mail]> wrote:

> On Tue, 2016-06-28 at 13:36 +0200, Emese Revfy wrote:
> > The nocapture gcc attribute can be on functions only.
> > The attribute takes one or more unsigned integer constants as parameters
> > that specify the function argument(s) of const char* type to initify.
> 
> Perhaps this should be const <type>*

For me function arguments are the values passed to a function call so
the const char* type is good because this is the only one that the plugin handles
(for now at least).

Rasmus Villemoes June 28, 2016, 8:50 p.m. UTC | #3

On Tue, Jun 28 2016, Emese Revfy <[e-mail]> wrote:

> The nocapture gcc attribute can be on functions only.
> The attribute takes one or more unsigned integer constants as parameters
> that specify the function argument(s) of const char* type to initify.
> If the marked argument is a vararg then the plugin initifies
> all vararg arguments.
>
> I couldn't test the arm, arm64 and powerpc architectures.
>
> Signed-off-by: Emese Revfy <[e-mail]>
> ---
>  arch/arm/include/asm/string.h     | 10 +++---
>  arch/arm64/include/asm/string.h   | 23 ++++++------
>  arch/powerpc/include/asm/string.h | 19 +++++-----
>  arch/x86/boot/string.h            |  4 +--
>  arch/x86/include/asm/string_32.h  | 21 +++++------
>  arch/x86/include/asm/string_64.h  | 18 +++++-----
>  arch/x86/kernel/hpet.c            |  2 +-
>  include/asm-generic/bug.h         |  6 ++--
>  include/linux/compiler-gcc.h      | 10 ++++--
>  include/linux/compiler.h          |  4 +++
>  include/linux/fs.h                |  5 +--
>  include/linux/printk.h            |  2 +-
>  include/linux/string.h            | 73 ++++++++++++++++++++-------------------
>  13 files changed, 107 insertions(+), 90 deletions(-)
>
> diff --git a/arch/arm/include/asm/string.h b/arch/arm/include/asm/string.h
> index cf4f3aa..3f68273 100644
> --- a/arch/arm/include/asm/string.h
> +++ b/arch/arm/include/asm/string.h
> @@ -7,19 +7,19 @@
>   */
>  
>  #define __HAVE_ARCH_STRRCHR
> -extern char * strrchr(const char * s, int c);
> +extern char * strrchr(const char * s, int c) __nocapture(1);
>  
>  #define __HAVE_ARCH_STRCHR
> -extern char * strchr(const char * s, int c);
> +extern char * strchr(const char * s, int c) __nocapture(1);
>  
>  #define __HAVE_ARCH_MEMCPY
> -extern void * memcpy(void *, const void *, __kernel_size_t);
> +extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);
>  

Why not also mark he dest argument of the various strcpy/memcpy/memset
functions as nocapture? It's no use for the initify plugin, but a static
analysis tool could for example use it to (better) diagnose resource leaks
(e.g., a buffer is kmalloc'ed and initialized with some *cpy, but then
something goes wrong, and the buffer isn't freed on the error path).
>  
>  #define __HAVE_ARCH_STRLEN
>  extern __kernel_size_t strlen(const char *);

Why not also mark strlen? I know that gcc optimizes strlen("literal")
away, but, again, there might be other uses even when the argument is
not a literal. One example is the plugin itself, which could deduce (or
suggest) __nocapture for a given function parameter if the parameter is
only passed on as __nocapture arguments.

> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> index 6f96247..4cdf266 100644
> --- a/include/asm-generic/bug.h
> +++ b/include/asm-generic/bug.h
> @@ -62,13 +62,13 @@ struct bug_entry {
>   * to provide better diagnostics.
>   */
>  #ifndef __WARN_TAINT
> -extern __printf(3, 4)
> +extern __printf(3, 4) __nocapture(1, 3, 4)
>  void warn_slowpath_fmt(const char *file, const int line,
>  		       const char *fmt, ...);
> -extern __printf(4, 5)
> +extern __printf(4, 5) __nocapture(1, 4, 5)
>  void warn_slowpath_fmt_taint(const char *file, const int line, unsigned taint,
>  			     const char *fmt, ...);

The 3,4 and 4,5 parts seem redundant when __printf automatically supplies those.

> -extern void warn_slowpath_null(const char *file, const int line);
> +extern __nocapture(1) void warn_slowpath_null(const char *file, const int line);
>  #define WANT_WARN_ON_SLOWPATH
>  #define __WARN()		warn_slowpath_null(__FILE__, __LINE__)
>  #define __WARN_printf(arg...)	warn_slowpath_fmt(__FILE__, __LINE__, arg)
> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> index df88c0a..192cea4 100644
> --- a/include/linux/compiler-gcc.h
> +++ b/include/linux/compiler-gcc.h
> @@ -116,8 +116,10 @@
>   */
>  #define __pure			__attribute__((pure))
>  #define __aligned(x)		__attribute__((aligned(x)))
> -#define __printf(a, b)		__attribute__((format(printf, a, b)))
> -#define __scanf(a, b)		__attribute__((format(scanf, a, b)))
> +#define __printf(a, b)		__attribute__((format(printf, a, b))) \
> +				__nocapture(a, b)
> +#define __scanf(a, b)		__attribute__((format(scanf, a, b))) \
> +				__nocapture(a, b)

So obviously the output parameters for scanf are never going to be
string literals, but I've already argued that one might as well put the
__nocapture on all relevant pointer arguments while we're churning the
headers, so keep this.

>  
> -extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
> -extern const char *kstrdup_const(const char *s, gfp_t gfp);
> -extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
> -extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
> +extern char *kstrdup(const char *s, gfp_t gfp) __malloc __nocapture(1);
> +extern const char *kstrdup_const(const char *s, gfp_t gfp) __nocapture(1);

OK, so this one is pretty dangerous, and probably wrong. If one does

  foo->bar = kstrdup_const(a-macro-that-might-be-a-string-literal)

in an .init function, foo->bar will very likely become dangling. Come to
think of it, I guess this means that __nocapture arguments must not only
not be stashed anywhere, the return value cannot point (in)to the same
object, which in turn then also disqualifies at least strchr(), memchr()
and the haystack parameter of strstr(). And bummer, that kills my
suggestion to add __nocapture to the dst parameters of *cpy, since they
return that argument.

Rasmus
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Joe Perches June 28, 2016, 9 p.m. UTC | #4

On Tue, 2016-06-28 at 22:40 +0200, Emese Revfy wrote:
> On Tue, 28 Jun 2016 09:43:31 -0700 Joe Perches <[e-mail]> wrote:
> > On Tue, 2016-06-28 at 13:36 +0200, Emese Revfy wrote:
> > > The nocapture gcc attribute can be on functions only.
> > > The attribute takes one or more unsigned integer constants as parameters
> > > that specify the function argument(s) of const char* type to initify.
> > Perhaps this should be const *
> For me function arguments are the values passed to a function call so
> the const char* type is good because this is the only one that the plugin handles
> (for now at least).

OK, but this function prototype specified takes a const void *

+extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);


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[e-mail] June 28, 2016, 9:38 p.m. UTC | #5

On 28 Jun 2016 at 22:50, Rasmus Villemoes wrote:

> > +extern const char *kstrdup_const(const char *s, gfp_t gfp) __nocapture(1);
> 
> OK, so this one is pretty dangerous, and probably wrong. If one does
> 
>   foo->bar = kstrdup_const(a-macro-that-might-be-a-string-literal)
> 
> in an .init function, foo->bar will very likely become dangling.

doesn't kstrdup_const omit the copy only for arguments that are stored in
.rodata (which doesn't include .init.rodata* and other init sections)?

cheers,
 PaX Team

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Rasmus Villemoes June 28, 2016, 10:41 p.m. UTC | #6

On Tue, Jun 28 2016, "PaX Team" <[e-mail]> wrote:

> On 28 Jun 2016 at 22:50, Rasmus Villemoes wrote:
>
>> > +extern const char *kstrdup_const(const char *s, gfp_t gfp) __nocapture(1);
>> 
>> OK, so this one is pretty dangerous, and probably wrong. If one does
>> 
>>   foo->bar = kstrdup_const(a-macro-that-might-be-a-string-literal)
>> 
>> in an .init function, foo->bar will very likely become dangling.
>
> doesn't kstrdup_const omit the copy only for arguments that are stored in
> .rodata (which doesn't include .init.rodata* and other init sections)?
>

Ah, right. But that's a little subtle. Also, it kind of defeats the
purpose of kstrdup_const - but it's probably not actually called with a
string literal all that often.

In any case, I think there's still a problem with strchr() and friends.

Rasmus
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Emese Revfy June 29, 2016, 6:39 p.m. UTC | #7

On Tue, 28 Jun 2016 22:50:55 +0200
Rasmus Villemoes <[e-mail]> wrote:

> On Tue, Jun 28 2016, Emese Revfy <[e-mail]> wrote: 
> > diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> > index 6f96247..4cdf266 100644
> > --- a/include/asm-generic/bug.h
> > +++ b/include/asm-generic/bug.h
> > @@ -62,13 +62,13 @@ struct bug_entry {
> >   * to provide better diagnostics.
> >   */
> >  #ifndef __WARN_TAINT
> > -extern __printf(3, 4)
> > +extern __printf(3, 4) __nocapture(1, 3, 4)
> >  void warn_slowpath_fmt(const char *file, const int line,
> >  		       const char *fmt, ...);
> > -extern __printf(4, 5)
> > +extern __printf(4, 5) __nocapture(1, 4, 5)
> >  void warn_slowpath_fmt_taint(const char *file, const int line, unsigned taint,
> >  			     const char *fmt, ...);
> 
> The 3,4 and 4,5 parts seem redundant when __printf automatically supplies those.

Thanks, I'll fix them in the next patch set.

Emese Revfy June 29, 2016, 6:42 p.m. UTC | #8

On Tue, 28 Jun 2016 14:00:57 -0700
Joe Perches <[e-mail]> wrote:

> On Tue, 2016-06-28 at 22:40 +0200, Emese Revfy wrote:
> > On Tue, 28 Jun 2016 09:43:31 -0700 Joe Perches <[e-mail]> wrote:
> > > On Tue, 2016-06-28 at 13:36 +0200, Emese Revfy wrote:
> > > > The nocapture gcc attribute can be on functions only.
> > > > The attribute takes one or more unsigned integer constants as parameters
> > > > that specify the function argument(s) of const char* type to initify.
> > > Perhaps this should be const *
> > For me function arguments are the values passed to a function call so
> > the const char* type is good because this is the only one that the plugin handles
> > (for now at least).
> 
> OK, but this function prototype specified takes a const void *
> 
> +extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);

What matters for the plugin is the type of the passed arguments (which can be const char*
in the current implementation), not that of the parameters.

Joe Perches June 30, 2016, 12:12 a.m. UTC | #9

On Wed, 2016-06-29 at 20:42 +0200, Emese Revfy wrote:
> On Tue, 28 Jun 2016 14:00:57 -0700 Joe Perches <[e-mail]> wrote:
> > On Tue, 2016-06-28 at 22:40 +0200, Emese Revfy wrote:
> > > On Tue, 28 Jun 2016 09:43:31 -0700 Joe Perches <[e-mail]> wrote:
> > > > On Tue, 2016-06-28 at 13:36 +0200, Emese Revfy wrote:
> > > > > The nocapture gcc attribute can be on functions only.
> > > > > The attribute takes one or more unsigned integer constants as parameters
> > > > > that specify the function argument(s) of const char* type to initify.
> > > > Perhaps this should be const <void>*
> > > For me function arguments are the values passed to a function call so
> > > the const char* type is good because this is the only one that the plugin handles
> > > (for now at least).
> > OK, but this function prototype specified takes a const void *
> > 
> > +extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);
> What matters for the plugin is the type of the passed arguments (which can be const char*
> in the current implementation), not that of the parameters.

And how does this work when the prototype requires the compiler to
implicit cast to const void * before calling the function?

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Emese Revfy July 1, 2016, 2:03 p.m. UTC | #10

On Wed, 29 Jun 2016 17:12:45 -0700
Joe Perches <[e-mail]> wrote:

> On Wed, 2016-06-29 at 20:42 +0200, Emese Revfy wrote:
> > On Tue, 28 Jun 2016 14:00:57 -0700 Joe Perches <[e-mail]> wrote:
> > > On Tue, 2016-06-28 at 22:40 +0200, Emese Revfy wrote:
> > > > On Tue, 28 Jun 2016 09:43:31 -0700 Joe Perches <[e-mail]> wrote:
> > > > > On Tue, 2016-06-28 at 13:36 +0200, Emese Revfy wrote:
> > > > > > The nocapture gcc attribute can be on functions only.
> > > > > > The attribute takes one or more unsigned integer constants as parameters
> > > > > > that specify the function argument(s) of const char* type to initify.
> > > > > Perhaps this should be const <void>*
> > > > For me function arguments are the values passed to a function call so
> > > > the const char* type is good because this is the only one that the plugin handles
> > > > (for now at least).
> > > OK, but this function prototype specified takes a const void *
> > > 
> > > +extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);
> > What matters for the plugin is the type of the passed arguments (which can be const char*
> > in the current implementation), not that of the parameters.
> 
> And how does this work when the prototype requires the compiler to
> implicit cast to const void * before calling the function?


The plugin searches for the nocapture attribute that does not depend on the type.
If the function argument is not a string constant just a pointer then
the plugin walks the data flow (use-def chain) and tries to find a string constant.
If there is a cast to void * then the use-def chain will walk across it.

Patch

diff --git a/arch/arm/include/asm/string.h b/arch/arm/include/asm/string.h
index cf4f3aa..3f68273 100644
--- a/arch/arm/include/asm/string.h
+++ b/arch/arm/include/asm/string.h
@@ -7,19 +7,19 @@ 
  */
 
 #define __HAVE_ARCH_STRRCHR
-extern char * strrchr(const char * s, int c);
+extern char * strrchr(const char * s, int c) __nocapture(1);
 
 #define __HAVE_ARCH_STRCHR
-extern char * strchr(const char * s, int c);
+extern char * strchr(const char * s, int c) __nocapture(1);
 
 #define __HAVE_ARCH_MEMCPY
-extern void * memcpy(void *, const void *, __kernel_size_t);
+extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2);
 
 #define __HAVE_ARCH_MEMMOVE
-extern void * memmove(void *, const void *, __kernel_size_t);
+extern void * memmove(void *, const void *, __kernel_size_t) __nocapture(2);
 
 #define __HAVE_ARCH_MEMCHR
-extern void * memchr(const void *, int, __kernel_size_t);
+extern void * memchr(const void *, int, __kernel_size_t) __nocapture(1);
 
 #define __HAVE_ARCH_MEMSET
 extern void * memset(void *, int, __kernel_size_t);
diff --git a/arch/arm64/include/asm/string.h b/arch/arm64/include/asm/string.h
index 2eb714c..0b3662b 100644
--- a/arch/arm64/include/asm/string.h
+++ b/arch/arm64/include/asm/string.h
@@ -17,40 +17,41 @@ 
 #define __ASM_STRING_H
 
 #define __HAVE_ARCH_STRRCHR
-extern char *strrchr(const char *, int c);
+extern char *strrchr(const char *, int c) __nocapture(1);
 
 #define __HAVE_ARCH_STRCHR
-extern char *strchr(const char *, int c);
+extern char *strchr(const char *, int c) __nocapture(1);
 
 #define __HAVE_ARCH_STRCMP
-extern int strcmp(const char *, const char *);
+extern int strcmp(const char *, const char *) __nocapture(1, 2);
 
 #define __HAVE_ARCH_STRNCMP
-extern int strncmp(const char *, const char *, __kernel_size_t);
+extern int
+strncmp(const char *, const char *, __kernel_size_t) __nocapture(1, 2);
 
 #define __HAVE_ARCH_STRLEN
 extern __kernel_size_t strlen(const char *);
 
 #define __HAVE_ARCH_STRNLEN
-extern __kernel_size_t strnlen(const char *, __kernel_size_t);
+extern __kernel_size_t strnlen(const char *, __kernel_size_t) __nocapture(1);
 
 #define __HAVE_ARCH_MEMCPY
-extern void *memcpy(void *, const void *, __kernel_size_t);
-extern void *__memcpy(void *, const void *, __kernel_size_t);
+extern void *memcpy(void *, const void *, __kernel_size_t) __nocapture(2);
+extern void *__memcpy(void *, const void *, __kernel_size_t) __nocapture(2);
 
 #define __HAVE_ARCH_MEMMOVE
-extern void *memmove(void *, const void *, __kernel_size_t);
-extern void *__memmove(void *, const void *, __kernel_size_t);
+extern void *memmove(void *, const void *, __kernel_size_t) __nocapture(2);
+extern void *__memmove(void *, const void *, __kernel_size_t) __nocapture(2);
 
 #define __HAVE_ARCH_MEMCHR
-extern void *memchr(const void *, int, __kernel_size_t);
+extern void *memchr(const void *, int, __kernel_size_t) __nocapture(1);
 
 #define __HAVE_ARCH_MEMSET
 extern void *memset(void *, int, __kernel_size_t);
 extern void *__memset(void *, int, __kernel_size_t);
 
 #define __HAVE_ARCH_MEMCMP
-extern int memcmp(const void *, const void *, size_t);
+extern int memcmp(const void *, const void *, size_t) __nocapture(1, 2);
 
 
 #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
index e40010a..b29fc74 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -15,17 +15,18 @@ 
 #define __HAVE_ARCH_MEMCMP
 #define __HAVE_ARCH_MEMCHR
 
-extern char * strcpy(char *,const char *);
-extern char * strncpy(char *,const char *, __kernel_size_t);
+extern char * strcpy(char *,const char *) __nocapture(2);
+extern char * strncpy(char *,const char *, __kernel_size_t) __nocapture(2);
 extern __kernel_size_t strlen(const char *);
-extern int strcmp(const char *,const char *);
-extern int strncmp(const char *, const char *, __kernel_size_t);
-extern char * strcat(char *, const char *);
+extern int strcmp(const char *,const char *) __nocapture(1, 2);
+extern int
+strncmp(const char *, const char *, __kernel_size_t) __nocapture(1, 2);
+extern char * strcat(char *, const char *) __nocapture(2);
 extern void * memset(void *,int,__kernel_size_t);
-extern void * memcpy(void *,const void *,__kernel_size_t);
-extern void * memmove(void *,const void *,__kernel_size_t);
-extern int memcmp(const void *,const void *,__kernel_size_t);
-extern void * memchr(const void *,int,__kernel_size_t);
+extern void * memcpy(void *,const void *,__kernel_size_t) __nocapture(2);
+extern void * memmove(void *,const void *,__kernel_size_t) __nocapture(2);
+extern int memcmp(const void *,const void *,__kernel_size_t) __nocapture(1, 2);
+extern void * memchr(const void *,int,__kernel_size_t) __nocapture(1);
 
 #endif /* __KERNEL__ */
 
diff --git a/arch/x86/boot/string.h b/arch/x86/boot/string.h
index 725e820..d7ea2759 100644
--- a/arch/x86/boot/string.h
+++ b/arch/x86/boot/string.h
@@ -6,9 +6,9 @@ 
 #undef memset
 #undef memcmp
 
-void *memcpy(void *dst, const void *src, size_t len);
+void *memcpy(void *dst, const void *src, size_t len) __nocapture(2);
 void *memset(void *dst, int c, size_t len);
-int memcmp(const void *s1, const void *s2, size_t len);
+int memcmp(const void *s1, const void *s2, size_t len) __nocapture(1, 2);
 
 /*
  * Access builtin version by default. If one needs to use optimized version,
diff --git a/arch/x86/include/asm/string_32.h b/arch/x86/include/asm/string_32.h
index 3d3e835..b94699b 100644
--- a/arch/x86/include/asm/string_32.h
+++ b/arch/x86/include/asm/string_32.h
@@ -6,25 +6,26 @@ 
 /* Let gcc decide whether to inline or use the out of line functions */
 
 #define __HAVE_ARCH_STRCPY
-extern char *strcpy(char *dest, const char *src);
+extern char *strcpy(char *dest, const char *src) __nocapture(2);
 
 #define __HAVE_ARCH_STRNCPY
-extern char *strncpy(char *dest, const char *src, size_t count);
+extern char *strncpy(char *dest, const char *src, size_t count) __nocapture(2);
 
 #define __HAVE_ARCH_STRCAT
-extern char *strcat(char *dest, const char *src);
+extern char *strcat(char *dest, const char *src) __nocapture(2);
 
 #define __HAVE_ARCH_STRNCAT
-extern char *strncat(char *dest, const char *src, size_t count);
+extern char *strncat(char *dest, const char *src, size_t count) __nocapture(2);
 
 #define __HAVE_ARCH_STRCMP
-extern int strcmp(const char *cs, const char *ct);
+extern int strcmp(const char *cs, const char *ct) __nocapture(1, 2);
 
 #define __HAVE_ARCH_STRNCMP
-extern int strncmp(const char *cs, const char *ct, size_t count);
+extern int
+strncmp(const char *cs, const char *ct, size_t count) __nocapture(1, 2);
 
 #define __HAVE_ARCH_STRCHR
-extern char *strchr(const char *s, int c);
+extern char *strchr(const char *s, int c) __nocapture(1);
 
 #define __HAVE_ARCH_STRLEN
 extern size_t strlen(const char *s);
@@ -197,12 +198,12 @@  static inline void *__memcpy3d(void *to, const void *from, size_t len)
 #endif
 
 #define __HAVE_ARCH_MEMMOVE
-void *memmove(void *dest, const void *src, size_t n);
+void *memmove(void *dest, const void *src, size_t n) __nocapture(2);
 
 #define memcmp __builtin_memcmp
 
 #define __HAVE_ARCH_MEMCHR
-extern void *memchr(const void *cs, int c, size_t count);
+extern void *memchr(const void *cs, int c, size_t count) __nocapture(1);
 
 static inline void *__memset_generic(void *s, char c, size_t count)
 {
@@ -247,7 +248,7 @@  extern size_t strnlen(const char *s, size_t count);
 /* end of additional stuff */
 
 #define __HAVE_ARCH_STRSTR
-extern char *strstr(const char *cs, const char *ct);
+extern char *strstr(const char *cs, const char *ct) __nocapture(1, 2);
 
 /*
  * This looks horribly ugly, but the compiler can optimize it totally,
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 90dbbd9..aff2c28 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -27,8 +27,8 @@  static __always_inline void *__inline_memcpy(void *to, const void *from, size_t
    function. */
 
 #define __HAVE_ARCH_MEMCPY 1
-extern void *memcpy(void *to, const void *from, size_t len);
-extern void *__memcpy(void *to, const void *from, size_t len);
+extern void *memcpy(void *to, const void *from, size_t len) __nocapture(2);
+extern void *__memcpy(void *to, const void *from, size_t len) __nocapture(2);
 
 #ifndef CONFIG_KMEMCHECK
 #if (__GNUC__ == 4 && __GNUC_MINOR__ < 3) || __GNUC__ < 4
@@ -56,14 +56,14 @@  void *memset(void *s, int c, size_t n);
 void *__memset(void *s, int c, size_t n);
 
 #define __HAVE_ARCH_MEMMOVE
-void *memmove(void *dest, const void *src, size_t count);
-void *__memmove(void *dest, const void *src, size_t count);
+void *memmove(void *dest, const void *src, size_t count) __nocapture(2);
+void *__memmove(void *dest, const void *src, size_t count) __nocapture(2);
 
-int memcmp(const void *cs, const void *ct, size_t count);
+int memcmp(const void *cs, const void *ct, size_t count) __nocapture(1, 2);
 size_t strlen(const char *s);
-char *strcpy(char *dest, const char *src);
-char *strcat(char *dest, const char *src);
-int strcmp(const char *cs, const char *ct);
+char *strcpy(char *dest, const char *src) __nocapture(2);
+char *strcat(char *dest, const char *src) __nocapture(2);
+int strcmp(const char *cs, const char *ct) __nocapture(1, 2);
 
 #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
 
@@ -89,7 +89,7 @@  int strcmp(const char *cs, const char *ct);
  *
  * Return 0 for success, -EFAULT for fail
  */
-int memcpy_mcsafe(void *dst, const void *src, size_t cnt);
+int memcpy_mcsafe(void *dst, const void *src, size_t cnt) __nocapture(2);
 
 #endif /* __KERNEL__ */
 
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index f112af7..acf9e16 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -136,7 +136,7 @@  int is_hpet_enabled(void)
 }
 EXPORT_SYMBOL_GPL(is_hpet_enabled);
 
-static void _hpet_print_config(const char *function, int line)
+static void __nocapture(1) _hpet_print_config(const char *function, int line)
 {
 	u32 i, timers, l, h;
 	printk(KERN_INFO "hpet: %s(%d):\n", function, line);
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 6f96247..4cdf266 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -62,13 +62,13 @@  struct bug_entry {
  * to provide better diagnostics.
  */
 #ifndef __WARN_TAINT
-extern __printf(3, 4)
+extern __printf(3, 4) __nocapture(1, 3, 4)
 void warn_slowpath_fmt(const char *file, const int line,
 		       const char *fmt, ...);
-extern __printf(4, 5)
+extern __printf(4, 5) __nocapture(1, 4, 5)
 void warn_slowpath_fmt_taint(const char *file, const int line, unsigned taint,
 			     const char *fmt, ...);
-extern void warn_slowpath_null(const char *file, const int line);
+extern __nocapture(1) void warn_slowpath_null(const char *file, const int line);
 #define WANT_WARN_ON_SLOWPATH
 #define __WARN()		warn_slowpath_null(__FILE__, __LINE__)
 #define __WARN_printf(arg...)	warn_slowpath_fmt(__FILE__, __LINE__, arg)
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index df88c0a..192cea4 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -116,8 +116,10 @@ 
  */
 #define __pure			__attribute__((pure))
 #define __aligned(x)		__attribute__((aligned(x)))
-#define __printf(a, b)		__attribute__((format(printf, a, b)))
-#define __scanf(a, b)		__attribute__((format(scanf, a, b)))
+#define __printf(a, b)		__attribute__((format(printf, a, b))) \
+				__nocapture(a, b)
+#define __scanf(a, b)		__attribute__((format(scanf, a, b))) \
+				__nocapture(a, b)
 #define __attribute_const__	__attribute__((__const__))
 #define __maybe_unused		__attribute__((unused))
 #define __always_unused		__attribute__((unused))
@@ -193,6 +195,10 @@ 
 # define __latent_entropy	__attribute__((latent_entropy))
 #endif
 
+#ifdef INITIFY_PLUGIN
+#define __nocapture(...) __attribute__((nocapture(__VA_ARGS__)))
+#endif
+
 /*
  * Mark a position in code as unreachable.  This can be used to
  * suppress control flow warnings after asm blocks that transfer
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c65327b..8a02dae 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -429,6 +429,10 @@  static __always_inline void __write_once_size(volatile void *p, void *res, int s
 # define __latent_entropy
 #endif
 
+#ifndef __nocapture
+# define __nocapture(...)
+#endif
+
 /*
  * Tell gcc if a function is cold. The compiler will assume any path
  * directly leading to the call is unlikely.
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dd28814..e3c7191 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2426,8 +2426,9 @@  extern int register_chrdev_region(dev_t, unsigned, const char *);
 extern int __register_chrdev(unsigned int major, unsigned int baseminor,
 			     unsigned int count, const char *name,
 			     const struct file_operations *fops);
-extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
-				unsigned int count, const char *name);
+extern __nocapture(4) void __unregister_chrdev(unsigned int major,
+				unsigned int baseminor, unsigned int count,
+				const char *name);
 extern void unregister_chrdev_region(dev_t, unsigned);
 extern void chrdev_show(struct seq_file *,off_t);
 
diff --git a/include/linux/printk.h b/include/linux/printk.h
index f4da695..b504798 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -163,7 +163,7 @@  __printf(1, 2) __cold int printk_deferred(const char *fmt, ...);
  * with all other unrelated printk_ratelimit() callsites.  Instead use
  * printk_ratelimited() or plain old __ratelimit().
  */
-extern int __printk_ratelimit(const char *func);
+extern int __printk_ratelimit(const char *func) __nocapture(1);
 #define printk_ratelimit() __printk_ratelimit(__func__)
 extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 				   unsigned int interval_msec);
diff --git a/include/linux/string.h b/include/linux/string.h
index 26b6f6a..536e733 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -18,51 +18,52 @@  extern void *memdup_user_nul(const void __user *, size_t);
 #include <asm/string.h>
 
 #ifndef __HAVE_ARCH_STRCPY
-extern char * strcpy(char *,const char *);
+extern char * strcpy(char *,const char *) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRNCPY
-extern char * strncpy(char *,const char *, __kernel_size_t);
+extern char * strncpy(char *,const char *, __kernel_size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRLCPY
-size_t strlcpy(char *, const char *, size_t);
+size_t strlcpy(char *, const char *, size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRSCPY
-ssize_t __must_check strscpy(char *, const char *, size_t);
+ssize_t __must_check strscpy(char *, const char *, size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRCAT
-extern char * strcat(char *, const char *);
+extern char * strcat(char *, const char *) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRNCAT
-extern char * strncat(char *, const char *, __kernel_size_t);
+extern char * strncat(char *, const char *, __kernel_size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRLCAT
-extern size_t strlcat(char *, const char *, __kernel_size_t);
+extern size_t strlcat(char *, const char *, __kernel_size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRCMP
-extern int strcmp(const char *,const char *);
+extern int strcmp(const char *,const char *) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRNCMP
-extern int strncmp(const char *,const char *,__kernel_size_t);
+extern int strncmp(const char *,const char *,__kernel_size_t) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRCASECMP
-extern int strcasecmp(const char *s1, const char *s2);
+extern int strcasecmp(const char *s1, const char *s2) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRNCASECMP
-extern int strncasecmp(const char *s1, const char *s2, size_t n);
+extern int
+strncasecmp(const char *s1, const char *s2, size_t n) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRCHR
-extern char * strchr(const char *,int);
+extern char * strchr(const char *,int) __nocapture(1);
 #endif
 #ifndef __HAVE_ARCH_STRCHRNUL
-extern char * strchrnul(const char *,int);
+extern char * strchrnul(const char *,int) __nocapture(1);
 #endif
 #ifndef __HAVE_ARCH_STRNCHR
-extern char * strnchr(const char *, size_t, int);
+extern char * strnchr(const char *, size_t, int) __nocapture(1);
 #endif
 #ifndef __HAVE_ARCH_STRRCHR
-extern char * strrchr(const char *,int);
+extern char * strrchr(const char *,int) __nocapture(1);
 #endif
-extern char * __must_check skip_spaces(const char *);
+extern char * __must_check skip_spaces(const char *) __nocapture(1);
 
 extern char *strim(char *);
 
@@ -72,10 +73,10 @@  static inline __must_check char *strstrip(char *str)
 }
 
 #ifndef __HAVE_ARCH_STRSTR
-extern char * strstr(const char *, const char *);
+extern char * strstr(const char *, const char *) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRNSTR
-extern char * strnstr(const char *, const char *, size_t);
+extern char * strnstr(const char *, const char *, size_t) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRLEN
 extern __kernel_size_t strlen(const char *);
@@ -84,51 +85,51 @@  extern __kernel_size_t strlen(const char *);
 extern __kernel_size_t strnlen(const char *,__kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_STRPBRK
-extern char * strpbrk(const char *,const char *);
+extern char * strpbrk(const char *,const char *) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRSEP
-extern char * strsep(char **,const char *);
+extern char * strsep(char **,const char *) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_STRSPN
-extern __kernel_size_t strspn(const char *,const char *);
+extern __kernel_size_t strspn(const char *,const char *) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_STRCSPN
-extern __kernel_size_t strcspn(const char *,const char *);
+extern __kernel_size_t strcspn(const char *,const char *) __nocapture(1, 2);
 #endif
 
 #ifndef __HAVE_ARCH_MEMSET
 extern void * memset(void *,int,__kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_MEMCPY
-extern void * memcpy(void *,const void *,__kernel_size_t);
+extern void * memcpy(void *,const void *,__kernel_size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_MEMMOVE
-extern void * memmove(void *,const void *,__kernel_size_t);
+extern void * memmove(void *,const void *,__kernel_size_t) __nocapture(2);
 #endif
 #ifndef __HAVE_ARCH_MEMSCAN
 extern void * memscan(void *,int,__kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_MEMCMP
-extern int memcmp(const void *,const void *,__kernel_size_t);
+extern int memcmp(const void *,const void *,__kernel_size_t) __nocapture(1, 2);
 #endif
 #ifndef __HAVE_ARCH_MEMCHR
-extern void * memchr(const void *,int,__kernel_size_t);
+extern void * memchr(const void *,int,__kernel_size_t) __nocapture(1);
 #endif
-void *memchr_inv(const void *s, int c, size_t n);
+void *memchr_inv(const void *s, int c, size_t n) __nocapture(1);
 char *strreplace(char *s, char old, char new);
 
 extern void kfree_const(const void *x);
 
-extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
-extern const char *kstrdup_const(const char *s, gfp_t gfp);
-extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
-extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
+extern char *kstrdup(const char *s, gfp_t gfp) __malloc __nocapture(1);
+extern const char *kstrdup_const(const char *s, gfp_t gfp) __nocapture(1);
+extern char *kstrndup(const char *s, size_t len, gfp_t gfp) __nocapture(1);
+extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __nocapture(1);
 
 extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
 extern void argv_free(char **argv);
 
-extern bool sysfs_streq(const char *s1, const char *s2);
-extern int kstrtobool(const char *s, bool *res);
+extern bool sysfs_streq(const char *s1, const char *s2) __nocapture(1, 2);
+extern int kstrtobool(const char *s, bool *res) __nocapture(1);
 static inline int strtobool(const char *s, bool *res)
 {
 	return kstrtobool(s, res);
@@ -137,8 +138,10 @@  static inline int strtobool(const char *s, bool *res)
 int match_string(const char * const *array, size_t n, const char *string);
 
 #ifdef CONFIG_BINARY_PRINTF
-int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
-int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
+int vbin_printf(u32 *bin_buf, size_t size, const char *fmt,
+		va_list args) __nocapture(3);
+int bstr_printf(char *buf, size_t size, const char *fmt,
+		const u32 *bin_buf) __nocapture(3);
 int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
 #endif