The patch titled
Subject: kasan: show gcc version requirements in Kconfig and Documentation
has been added to the -mm tree. Its filename is
kasan-show-gcc-version-requirements-in-kconfig-and-documentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-show-gcc-version-requirements-in-kconfig-and-documentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-show-gcc-version-requirements-in-kconfig-and-documentation.patch
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From: Joe Perches <joe@xxxxxxxxxxx>
Subject: kasan: show gcc version requirements in Kconfig and Documentation
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@xxxxxxxxxxx>
Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/kasan.txt | 8 +++++---
lib/Kconfig.kasan | 8 ++++++--
2 files changed, 11 insertions(+), 5 deletions(-)
diff -puN Documentation/kasan.txt~kasan-show-gcc-version-requirements-in-kconfig-and-documentation Documentation/kasan.txt
--- a/Documentation/kasan.txt~kasan-show-gcc-version-requirements-in-kconfig-and-documentation
+++ a/Documentation/kasan.txt
@@ -9,7 +9,9 @@ a fast and comprehensive solution for fi
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 -puN lib/Kconfig.kasan~kasan-show-gcc-version-requirements-in-kconfig-and-documentation lib/Kconfig.kasan
--- a/lib/Kconfig.kasan~kasan-show-gcc-version-requirements-in-kconfig-and-documentation
+++ a/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
_
Patches currently in -mm which might be from joe@xxxxxxxxxxx are
origin.patch
compiler-gcch-neatening.patch
compiler-gcc-integrate-the-various-compiler-gcch-files.patch
kasan-show-gcc-version-requirements-in-kconfig-and-documentation.patch
ocfs2-neaten-do_error-ocfs2_error-and-ocfs2_abort.patch
mm-utilc-add-kstrimdup.patch
linux-next.patch
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