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89d3c87e20
It's recommended to have slub's user tracking enabled with CONFIG_KASAN,
because:
a) User tracking disables slab merging which improves
detecting out-of-bounds accesses.
b) User tracking metadata acts as redzone which also improves
detecting out-of-bounds accesses.
c) User tracking provides additional information about object.
This information helps to understand bugs.
Currently it is not enabled by default. Besides recompiling the kernel
with KASAN and reinstalling it, user also have to change the boot cmdline,
which is not very handy.
Enable slub user tracking by default with KASAN=y, since there is no good
reason to not do this.
[akpm@linux-foundation.org: little fixes, per David]
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
54 lines
1.6 KiB
Plaintext
54 lines
1.6 KiB
Plaintext
config HAVE_ARCH_KASAN
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bool
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if HAVE_ARCH_KASAN
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config KASAN
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bool "KASan: runtime memory debugger"
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depends on SLUB_DEBUG
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select CONSTRUCTORS
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help
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Enables kernel address sanitizer - runtime memory debugger,
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designed to find out-of-bounds accesses and use-after-free bugs.
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This is strictly a debugging feature and it requires a gcc version
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of 4.9.2 or later. Detection of out of bounds accesses to stack or
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global variables requires gcc 5.0 or later.
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This feature consumes about 1/8 of available memory and brings about
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~x3 performance slowdown.
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For better error detection enable CONFIG_STACKTRACE.
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choice
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prompt "Instrumentation type"
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depends on KASAN
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default KASAN_OUTLINE
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config KASAN_OUTLINE
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bool "Outline instrumentation"
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help
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Before every memory access compiler insert function call
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__asan_load*/__asan_store*. These functions performs check
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of shadow memory. This is slower than inline instrumentation,
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however it doesn't bloat size of kernel's .text section so
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much as inline does.
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config KASAN_INLINE
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bool "Inline instrumentation"
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help
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Compiler directly inserts code checking shadow memory before
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memory accesses. This is faster than outline (in some workloads
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it gives about x2 boost over outline instrumentation), but
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make kernel's .text size much bigger.
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This requires a gcc version of 5.0 or later.
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endchoice
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config TEST_KASAN
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tristate "Module for testing kasan for bug detection"
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depends on m && KASAN
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help
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This is a test module doing various nasty things like
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out of bounds accesses, use after free. It is useful for testing
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kernel debugging features like kernel address sanitizer.
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endif
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