| Message ID | 20200924040152.30851-1-walter-zh.wu@mediatek.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | kasan: add workqueue and timer stack for generic KASAN | expand |
> --- > Documentation/dev-tools/kasan.rst | 5 +++-- > kernel/time/timer.c | 3 +++ > kernel/workqueue.c | 3 +++ > lib/test_kasan_module.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > mm/kasan/report.c | 4 ++-- > 5 files changed, 66 insertions(+), 4 deletions(-) While at it, can you remove a mention of call_rcu() from the kasan_record_aux_stack() implementation, as it is no more RCU-specific?
On Thu, 2020-09-24 at 13:51 +0200, 'Alexander Potapenko' via kasan-dev wrote: > > --- > > Documentation/dev-tools/kasan.rst | 5 +++-- > > kernel/time/timer.c | 3 +++ > > kernel/workqueue.c | 3 +++ > > lib/test_kasan_module.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > mm/kasan/report.c | 4 ++-- > > 5 files changed, 66 insertions(+), 4 deletions(-) > > While at it, can you remove a mention of call_rcu() from the > kasan_record_aux_stack() implementation, as it is no more > RCU-specific? > Thank you for your reminder. v5 will do it. Walter
On Thu, Sep 24 2020 at 12:01, Walter Wu 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 stack information. It is useful for programmers > to solve use-after-free or double-free memory issue. > > Generic KASAN also records the last two workqueue and timer stacks and > prints 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 How are these links useful for people who do not have a gurgle account?
On Wed, Sep 30, 2020 at 5:29 PM Thomas Gleixner <tglx@linutronix.de> wrote: > > On Thu, Sep 24 2020 at 12:01, Walter Wu 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 stack information. It is useful for programmers > > to solve use-after-free or double-free memory issue. > > > > Generic KASAN also records the last two workqueue and timer stacks and > > prints them in KASAN report. It is only suitable for generic KASAN. Walter, did you mail v5? Checking statuses of KASAN issues and this seems to be not in linux-next. > > [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 > > How are these links useful for people who do not have a gurgle account? This is a public mailing list archive, so effectively the same way as lore links ;)
On Tue, Dec 1, 2020 at 12:17 PM Walter Wu <walter-zh.wu@mediatek.com> wrote: > > Hi Dmitry, > > On Tue, 2020-12-01 at 08:59 +0100, 'Dmitry Vyukov' via kasan-dev wrote: > > On Wed, Sep 30, 2020 at 5:29 PM Thomas Gleixner <tglx@linutronix.de> wrote: > > > > > > On Thu, Sep 24 2020 at 12:01, Walter Wu 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 stack information. It is useful for programmers > > > > to solve use-after-free or double-free memory issue. > > > > > > > > Generic KASAN also records the last two workqueue and timer stacks and > > > > prints them in KASAN report. It is only suitable for generic KASAN. > > > > Walter, did you mail v5? > > Checking statuses of KASAN issues and this seems to be not in linux-next. > > > > Sorry for the delay in responding to this patch. I'm busy these few > months, so that suspend processing it. > Yes, I will send it next week. But v4 need to confirm the timer stack is > useful. I haven't found an example. Do you have some suggestion about > timer? Good question. We had some use-after-free's what mention call_timer_fn: https://groups.google.com/g/syzkaller-bugs/search?q=%22kasan%22%20%22use-after-free%22%20%22expire_timers%22%20%22call_timer_fn%22%20 In the reports I checked call_timer_fn appears in the "access" stack rather in the "free" stack. Looking at these reports I cannot conclude that do_init_timer stack would be useful. I am mildly leaning towards not memorizing do_init_timer stack for now (until we have clear use cases) as the number of aux stacks is very limited (2).
On Tue, Dec 01 2020 at 08:59, Dmitry Vyukov wrote: > On Wed, Sep 30, 2020 at 5:29 PM Thomas Gleixner <tglx@linutronix.de> wrote: >> On Thu, Sep 24 2020 at 12:01, Walter Wu 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 stack information. It is useful for programmers >> > to solve use-after-free or double-free memory issue. >> > >> > Generic KASAN also records the last two workqueue and timer stacks and >> > prints them in KASAN report. It is only suitable for generic KASAN. > > Walter, did you mail v5? > Checking statuses of KASAN issues and this seems to be not in linux-next. > >> > [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 >> >> How are these links useful for people who do not have a gurgle account? > > This is a public mailing list archive, so effectively the same way as > lore links ;) Just that it asked me to log in last time. That's why I wrote the above. Today it does not, odd. Thanks, tglx
On Tue, Dec 1, 2020 at 3:13 PM Thomas Gleixner <tglx@linutronix.de> 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 stack information. It is useful for programmers > >> > to solve use-after-free or double-free memory issue. > >> > > >> > Generic KASAN also records the last two workqueue and timer stacks and > >> > prints them in KASAN report. It is only suitable for generic KASAN. > > > > Walter, did you mail v5? > > Checking statuses of KASAN issues and this seems to be not in linux-next. > > > >> > [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 > >> > >> How are these links useful for people who do not have a gurgle account? > > > > This is a public mailing list archive, so effectively the same way as > > lore links ;) > > Just that it asked me to log in last time. That's why I wrote the > above. Today it does not, odd. Some random permissions settings changes were observed before, so I can believe that.