This adds the documentation for the KASAN_RCU_STACK_RECORD config option. Signed-off-by: Walter Wu <walter-zh...@mediatek.com> Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: Alexander Potapenko <gli...@google.com> Cc: Jonathan Corbet <cor...@lwn.net> --- Documentation/dev-tools/kasan.rst | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index c652d740735d..368ff0dad0d7 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -281,3 +281,24 @@ unmapped. This will require changes in arch-specific code. This allows ``VMAP_STACK`` support on x86, and can simplify support of architectures that do not have a fixed module region. + +CONFIG_KASAN_RCU_STACK_RECORD +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +With CONFIG_KASAN_RCU_STACK_RECORD, when call_rcu() is called, it will +store the call_rcu() call stack into slub alloc meta-data. The goal +is to print call_rcu() information in KASAN report. It is helpful for +use-after-free or double free memory issue. + +Record first and last call_rcu() call stack and print two call_rcu() +call stack in KASAN report. + +This option doesn't increase the cost of memory consumption, we add two +call_rcu() call stack into struct kasan_alloc_meta and size is 8 bytes. +Remove the free track from struct kasan_alloc_meta and size is 8 bytes. +So we don't enlarge the slub meta-data size. + +This option is only suitable for generic KASAN. Because the free track +is stored in freed object. so free track is valid information only when +it exists in the quarantine. If the slub object is in-use state, then +KASAN report doesn't print call_rcu() free track information. -- 2.18.0
