[PATCH v7 0/4] kasan: memorize and print call_rcu stack

From: Walter Wu
Date: Mon Jun 01 2020 - 01:09:07 EST


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:
kasan_save_stack+0x24/0x50
kasan_set_track+0x24/0x38
kasan_set_free_info+0x18/0x20
__kasan_slab_free+0x10c/0x170
kasan_slab_free+0x10/0x18
kfree+0x98/0x270
kasan_rcu_reclaim+0x1c/0x60

Last call_rcu():
kasan_save_stack+0x24/0x50
kasan_record_aux_stack+0xbc/0xd0
call_rcu+0x8c/0x580
kasan_rcu_uaf+0xf4/0xf8

Generic KASAN will record the last two call_rcu() call stacks and
print up to 2 call_rcu() call stacks in KASAN report. it is only
suitable for generic KASAN.

This feature considers the size of struct kasan_alloc_meta and
kasan_free_meta, we try to optimize the structure layout and size
, lets it get better memory consumption.

[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 v1:
- 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

Changes since v2:
- change recording from first/last to the last two call stacks
- move free track into kasan free meta
- init slab_free_meta on object slot creation
- modify documentation

Changes since v3:
- change variable name to be more clearly
- remove the redundant condition
- remove init free meta-data and increasing object condition

Changes since v4:
- add a macro KASAN_KMALLOC_FREETRACK in order to check whether
print free stack
- change printing message
- remove descriptions in Kocong.kasan

Changes since v5:
- reuse print_stack() in print_track()

Changes since v6:
- fix typo
- renamed the variable name in testcase

Walter Wu (4):
rcu: kasan: record and print call_rcu() call stack
kasan: record and print the free track
kasan: add tests for call_rcu stack recording
kasan: update documentation for generic kasan

Documentation/dev-tools/kasan.rst | 3 +++
include/linux/kasan.h | 2 ++
kernel/rcu/tree.c | 2 ++
lib/test_kasan.c | 30 ++++++++++++++++++++++++++++++
mm/kasan/common.c | 26 ++++----------------------
mm/kasan/generic.c | 43 +++++++++++++++++++++++++++++++++++++++++++
mm/kasan/generic_report.c | 1 +
mm/kasan/kasan.h | 23 +++++++++++++++++++++--
mm/kasan/quarantine.c | 1 +
mm/kasan/report.c | 54 +++++++++++++++++++++++++++---------------------------
mm/kasan/tags.c | 37 +++++++++++++++++++++++++++++++++++++
11 files changed, 171 insertions(+), 51 deletions(-)