[Devel] [PATCH rh7 01/39] kasan: show gcc version requirements in Kconfig and Documentation
aryabinin at virtuozzo.com
Thu Sep 14 19:51:18 MSK 2017
From: Joe Perches <joe at 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 at perches.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin at samsung.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(cherry picked from commit 01e76903f655a4d88c2e09d3182436c65f6e1213)
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
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 ee36ef1a64c0..67e62ed6a198 100644
@@ -9,7 +9,9 @@ a fast and comprehensive solution for finding use-after-free and out-of-bounds
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 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 and enable CONFIG_STACKTRACE.
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 4fecaedc80a2..777eda7d1ab4 100644
@@ -10,8 +10,11 @@ config KASAN
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.
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