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

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

On Mon, 2020-05-11 at 12:01 +0200, 'Dmitry Vyukov' via kasan-dev wrote:
> On Mon, May 11, 2020 at 4:24 AM Walter Wu <walter-zh.wu@mediatek.com> wrote:
> >
> > 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.
> 
> Hi Walter,
> 
> I am looking at this now.
> 
> I've upload the change to gerrit [1]
> https://linux-review.googlesource.com/c/linux/kernel/git/torvalds/linux/+/2458
> 
> I am not capable enough to meaningfully review such changes in this format...
> 
> [1] https://linux.googlesource.com/Documentation
> 

Hi Dmitry,

I don't fully understand your meaning, our patchset's format has
problem? or?


> 
> > 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(-)
> >
> > --
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>