| Message ID | 1454956782-5944-1-git-send-email-yang.shi@linaro.org |
|---|---|
| State | New |
| Headers | show |
Hi Steven, Any comment for this patch? Thanks, Yang On 2/9/2016 5:40 AM, Andrey Ryabinin wrote: > On 02/08/2016 09:39 PM, Yang Shi wrote: >> When enabling stack trace via "echo 1 > /proc/sys/kernel/stack_tracer_enabled", >> the below KASAN warning is triggered: >> >> BUG: KASAN: stack-out-of-bounds in check_stack+0x344/0x848 at addr ffffffc0689ebab8 >> Read of size 8 by task ksoftirqd/4/29 >> page:ffffffbdc3a27ac0 count:0 mapcount:0 mapping: (null) index:0x0 >> flags: 0x0() >> page dumped because: kasan: bad access detected >> CPU: 4 PID: 29 Comm: ksoftirqd/4 Not tainted 4.5.0-rc1 #129 >> Hardware name: Freescale Layerscape 2085a RDB Board (DT) >> Call trace: >> [<ffffffc000091300>] dump_backtrace+0x0/0x3a0 >> [<ffffffc0000916c4>] show_stack+0x24/0x30 >> [<ffffffc0009bbd78>] dump_stack+0xd8/0x168 >> [<ffffffc000420bb0>] kasan_report_error+0x6a0/0x920 >> [<ffffffc000421688>] kasan_report+0x70/0xb8 >> [<ffffffc00041f7f0>] __asan_load8+0x60/0x78 >> [<ffffffc0002e05c4>] check_stack+0x344/0x848 >> [<ffffffc0002e0c8c>] stack_trace_call+0x1c4/0x370 >> [<ffffffc0002af558>] ftrace_ops_no_ops+0x2c0/0x590 >> [<ffffffc00009f25c>] ftrace_graph_call+0x0/0x14 >> [<ffffffc0000881bc>] fpsimd_thread_switch+0x24/0x1e8 >> [<ffffffc000089864>] __switch_to+0x34/0x218 >> [<ffffffc0011e089c>] __schedule+0x3ac/0x15b8 >> [<ffffffc0011e1f6c>] schedule+0x5c/0x178 >> [<ffffffc0001632a8>] smpboot_thread_fn+0x350/0x960 >> [<ffffffc00015b518>] kthread+0x1d8/0x2b0 >> [<ffffffc0000874d0>] ret_from_fork+0x10/0x40 >> Memory state around the buggy address: >> ffffffc0689eb980: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f4 f4 f4 >> ffffffc0689eba00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 >>> ffffffc0689eba80: 00 00 f1 f1 f1 f1 00 f4 f4 f4 f3 f3 f3 f3 00 00 >> ^ >> ffffffc0689ebb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffffffc0689ebb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> >> The stacker tracer traverses the whole kernel stack when saving the max stack >> trace. It may touch the stack red zones to cause the warning. So, just disable >> the instrumentation to silence the warning. >> >> Signed-off-by: Yang Shi <yang.shi@linaro.org> > > Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> >
On 2/12/2016 11:35 AM, Steven Rostedt wrote: > On Mon, 8 Feb 2016 10:39:42 -0800 > Yang Shi <yang.shi@linaro.org> wrote: > >> >> Signed-off-by: Yang Shi <yang.shi@linaro.org> >> --- >> kernel/trace/trace_stack.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c >> index 202df6c..61e5e1e 100644 >> --- a/kernel/trace/trace_stack.c >> +++ b/kernel/trace/trace_stack.c >> @@ -156,7 +156,7 @@ check_stack(unsigned long ip, unsigned long *stack) >> for (; p < top && i < stack_trace_max.nr_entries; p++) { >> if (stack_dump_trace[i] == ULONG_MAX) >> break; >> - if (*p == stack_dump_trace[i]) { > > Can you add a comment explaining this. Something like: > > /* > * The READ_ONCE_NOCHECK() is used to let KASAN know that > * this is not an stack-out-of-bounds error. > */ Sure, will add in v2. Thanks, Yang > > Thanks, > > -- Steve > >> + if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) { >> stack_dump_trace[x] = stack_dump_trace[i++]; >> this_size = stack_trace_index[x++] = >> (top - p) * sizeof(unsigned long); >
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 202df6c..61e5e1e 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -156,7 +156,7 @@ check_stack(unsigned long ip, unsigned long *stack) for (; p < top && i < stack_trace_max.nr_entries; p++) { if (stack_dump_trace[i] == ULONG_MAX) break; - if (*p == stack_dump_trace[i]) { + if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) { stack_dump_trace[x] = stack_dump_trace[i++]; this_size = stack_trace_index[x++] = (top - p) * sizeof(unsigned long);