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Groups > linux.kernel > #1333112 > unrolled thread
| Started by | Yang Shi <yang.shi@linaro.org> |
|---|---|
| First post | 2016-02-12 22:10 +0100 |
| Last post | 2016-02-19 18:40 +0100 |
| Articles | 2 — 2 participants |
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[v2 PATCH] trace, kasan: silence Kasan warning in check_stack Yang Shi <yang.shi@linaro.org> - 2016-02-12 22:10 +0100
Re: [v2 PATCH] trace, kasan: silence Kasan warning in check_stack Steven Rostedt <rostedt@goodmis.org> - 2016-02-19 18:40 +0100
| From | Yang Shi <yang.shi@linaro.org> |
|---|---|
| Date | 2016-02-12 22:10 +0100 |
| Subject | [v2 PATCH] trace, kasan: silence Kasan warning in check_stack |
| Message-ID | <r1t8v-3TO-43@gated-at.bofh.it> |
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>
---
v2:
Add comment suggested by Steven
kernel/trace/trace_stack.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 202df6c..2a1abba 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -156,7 +156,11 @@ 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]) {
+ /*
+ * The READ_ONCE_NOCHECK is used to let KASAN know that
+ * this is not a stack-out-of-bounds error.
+ */
+ 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);
--
2.0.2
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| From | Steven Rostedt <rostedt@goodmis.org> |
|---|---|
| Date | 2016-02-19 18:40 +0100 |
| Message-ID | <r3Xc6-8z-29@gated-at.bofh.it> |
| In reply to | #1333112 |
On Fri, 12 Feb 2016 12:46:00 -0800 Yang Shi <yang.shi@linaro.org> 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> Applied, thanks! -- Steve
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