From: Joe Perches joe@perches.com
The documentation shows a need for gcc > 4.9.2, but it's really >=. The Kconfig entries don't show require versions so add them. Correct a latter/later typo too. Also mention that gcc 5 required to catch out of bounds accesses to global and stack variables.
Signed-off-by: Joe Perches joe@perches.com Signed-off-by: Andrey Ryabinin a.ryabinin@samsung.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org (cherry picked from commit 01e76903f655a4d88c2e09d3182436c65f6e1213) Signed-off-by: Alex Shi alex.shi@linaro.org --- Documentation/kasan.txt | 8 +++++--- lib/Kconfig.kasan | 8 ++++++-- 2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/Documentation/kasan.txt b/Documentation/kasan.txt index 092fc10..4692241 100644 --- a/Documentation/kasan.txt +++ b/Documentation/kasan.txt @@ -9,7 +9,9 @@ a fast and comprehensive solution for finding use-after-free and out-of-bounds bugs.
KASan uses compile-time instrumentation for checking every memory access, -therefore you will need a certain version of GCC > 4.9.2 +therefore you will need a gcc version of 4.9.2 or later. KASan could detect out +of bounds accesses to stack or global variables, but only if gcc 5.0 or later was +used to built the kernel.
Currently KASan is supported only for x86_64 architecture and requires that the kernel be built with the SLUB allocator. @@ -23,8 +25,8 @@ To enable KASAN configure kernel with:
and choose between CONFIG_KASAN_OUTLINE and CONFIG_KASAN_INLINE. Outline/inline is compiler instrumentation types. The former produces smaller binary the -latter is 1.1 - 2 times faster. Inline instrumentation requires GCC 5.0 or -latter. +latter is 1.1 - 2 times faster. Inline instrumentation requires a gcc version +of 5.0 or later.
Currently KASAN works only with the SLUB memory allocator. For better bug detection and nicer report, enable CONFIG_STACKTRACE and put diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 4fecaedc..777eda7 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -10,8 +10,11 @@ config KASAN help Enables kernel address sanitizer - runtime memory debugger, designed to find out-of-bounds accesses and use-after-free bugs. - This is strictly debugging feature. It consumes about 1/8 - of available memory and brings about ~x3 performance slowdown. + This is strictly a debugging feature and it requires a gcc version + of 4.9.2 or later. Detection of out of bounds accesses to stack or + global variables requires gcc 5.0 or later. + This feature consumes about 1/8 of available memory and brings about + ~x3 performance slowdown. For better error detection enable CONFIG_STACKTRACE, and add slub_debug=U to boot cmdline.
@@ -40,6 +43,7 @@ config KASAN_INLINE memory accesses. This is faster than outline (in some workloads it gives about x2 boost over outline instrumentation), but make kernel's .text size much bigger. + This requires a gcc version of 5.0 or later.
endchoice