[PATCH v2 0/3] kasan: memorize and print call_rcu stack

[Walter Wu <walter-zh.wu@mediatek.com>]

This patchset improves KASAN reports by making them to have
call_rcu() call stack information. It is useful for programmers
to solve use-after-free or double-free memory issue.

The KASAN report was as follows(cleaned up slightly):

BUG: KASAN: use-after-free in kasan_rcu_reclaim+0x58/0x60

Freed by task 0:
 save_stack+0x24/0x50
 __kasan_slab_free+0x110/0x178
 kasan_slab_free+0x10/0x18
 kfree+0x98/0x270
 kasan_rcu_reclaim+0x1c/0x60
 rcu_core+0x8b4/0x10f8
 rcu_core_si+0xc/0x18
 efi_header_end+0x238/0xa6c

First call_rcu() call stack:
 save_stack+0x24/0x50
 kasan_record_callrcu+0xc8/0xd8
 call_rcu+0x190/0x580
 kasan_rcu_uaf+0x1d8/0x278

Last call_rcu() call stack:
(stack is not available)

Generic KASAN will record first and last call_rcu() call stack
and print two call_rcu() call stack in KASAN report.

This feature doesn't increase the cost of memory consumption. It is
only suitable for generic KASAN.

[1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
[2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ

Changes since v2:
- remove new config option, default enable it in generic KASAN
- test this feature in SLAB/SLUB, it is pass.
- modify macro to be more clearly
- modify documentation

Walter Wu (3):
rcu/kasan: record and print call_rcu() call stack
kasan: record and print the free track
kasan: update documentation for generic kasan

Documentation/dev-tools/kasan.rst |  6 ++++++
include/linux/kasan.h             |  2 ++
kernel/rcu/tree.c                 |  4 ++++
lib/Kconfig.kasan                 |  2 ++
mm/kasan/common.c                 | 26 ++++----------------------
mm/kasan/generic.c                | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
mm/kasan/kasan.h                  | 23 +++++++++++++++++++++++
mm/kasan/report.c                 | 47 +++++++++++++++++++++--------------------------
mm/kasan/tags.c                   | 37 +++++++++++++++++++++++++++++++++++++
9 files changed, 149 insertions(+), 48 deletions(-)