On Mon, 24 Aug 2020 at 10:07, Walter Wu <walter-zh.wu@xxxxxxxxxxxx> wrote: > > Syzbot reports many UAF issues for workqueue or timer, see [1] and [2]. > In some of these access/allocation happened in process_one_work(), > we see the free stack is useless in KASAN report, it doesn't help > programmers to solve UAF on workqueue. The same may stand for times. > > This patchset improves KASAN reports by making them to have workqueue > queueing stack and timer queueing stack information. It is useful for > programmers to solve use-after-free or double-free memory issue. > > Generic KASAN will record the last two workqueue and timer stacks, > print them in KASAN report. It is only suitable for generic KASAN. > > [1]https://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22+process_one_work > [2]https://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22%20expire_timers > [3]https://bugzilla.kernel.org/show_bug.cgi?id=198437 > > Walter Wu (6): > timer: kasan: record timer stack > workqueue: kasan: record workqueue stack > kasan: print timer and workqueue stack > lib/test_kasan.c: add timer test case > lib/test_kasan.c: add workqueue test case > kasan: update documentation for generic kasan > > --- > > Changes since v1: > - Thanks for Marco and Thomas suggestion. > - Remove unnecessary code and fix commit log > - reuse kasan_record_aux_stack() and aux_stack > to record timer and workqueue stack. > - change the aux stack title for common name. Much cleaner. In general, Acked-by: Marco Elver <elver@xxxxxxxxxx> but I left some more comments. I'm a bit worried about the tests, because of KASAN-test KUnit rework, but probably not much we can do until these are added to -mm tree. Thanks, -- Marco
