From: Emese Revfy <[email protected]> The initify plugin attempts to analyze function arguments that have been marked correctly with the __nocapture attribute. However, due to code complexity, this is not always possible to verify. As a result, some __nocapture attributes need to be marked as excluded from the automatic verification. To do this, the __unverified_nocapture attribute is added. It is intedned to only be used on function parameters that are difficult for the plugin to analyze.
Signed-off-by: Emese Revfy <[email protected]> Signed-off-by: Kees Cook <[email protected]> --- include/linux/compiler-gcc.h | 8 ++++++++ include/linux/compiler.h | 4 ++++ lib/vsprintf.c | 4 ++-- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index cd4e9ffb00a7..fc0495e849ff 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -204,9 +204,17 @@ * been unmapped from memory. In order to identify functions that are confirmed * to not capture their arguments, the __nocapture() attribute is used so that * initify can better identify candidate variables. + * + * Arguments marked in this way are verified by the plugin, but sometimes + * code complexity and other limitiations will cause initify to not be able + * to check it correctly. For these cases, the __unverified_nocapture + * attribute can be added to disable this checking, overriding the plugin + * logic for cases that have been manually verified. This should not need + * to be used very often. */ #ifdef INITIFY_PLUGIN #define __nocapture(...) __attribute__((nocapture(__VA_ARGS__))) +#define __unverified_nocapture(...) __attribute__((unverified_nocapture(__VA_ARGS__))) #endif /* diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 8b3dcc790bb6..1bde420f07bb 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -437,6 +437,10 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s # define __nocapture(...) #endif +#ifndef __unverified_nocapture +# define __unverified_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/lib/vsprintf.c b/lib/vsprintf.c index a192761d338a..cb964b51f9f8 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -118,7 +118,7 @@ long long simple_strtoll(const char *cp, char **endp, unsigned int base) } EXPORT_SYMBOL(simple_strtoll); -static noinline_for_stack __nocapture(1) +static noinline_for_stack __nocapture(1) __unverified_nocapture(1) int skip_atoi(const char **s) { int i = 0; @@ -1570,7 +1570,7 @@ int kptr_restrict __read_mostly; * function pointers are really function descriptors, which contain a * pointer to the real address. */ -static noinline_for_stack __nocapture(1) +static noinline_for_stack __nocapture(1) __unverified_nocapture(1) char *pointer(const char *fmt, char *buf, char *end, void *ptr, struct printf_spec spec) { -- 2.7.4
