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Message-ID: <20221205132936.493245-1-liushixin2@huawei.com>
Date: Mon, 5 Dec 2022 21:29:36 +0800
From: Liu Shixin <liushixin2@...wei.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Changbin Du <changbin.du@...el.com>
CC: <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
Liu Shixin <liushixin2@...wei.com>
Subject: [PATCH] riscv: stacktrace: Fix missing the first frame
When running kfence_test, I found some testcases failed like this:
# test_out_of_bounds_read: EXPECTATION FAILED at mm/kfence/kfence_test.c:346
Expected report_matches(&expect) to be true, but is false
not ok 1 - test_out_of_bounds_read
The corresponding call-trace is:
BUG: KFENCE: out-of-bounds read in kunit_try_run_case+0x38/0x84
Out-of-bounds read at 0x(____ptrval____) (32B right of kfence-#10):
kunit_try_run_case+0x38/0x84
kunit_generic_run_threadfn_adapter+0x12/0x1e
kthread+0xc8/0xde
ret_from_exception+0x0/0xc
The kfence_test using the first frame of call trace to check whether the
testcase is succeed or not. Patch a7c5c7e8ff78 skip first frame for all
case, which results the kfence_test failed. Indeed, we only need to skip
the first frame for case (task==NULL || task==current).
With this patch, the call-trace will be:
BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0x88/0x19e
Out-of-bounds read at 0x(____ptrval____) (1B left of kfence-#7):
test_out_of_bounds_read+0x88/0x19e
kunit_try_run_case+0x38/0x84
kunit_generic_run_threadfn_adapter+0x12/0x1e
kthread+0xc8/0xde
ret_from_exception+0x0/0xc
Fixes: a7c5c7e8ff78 ("riscv: eliminate unreliable __builtin_frame_address(1)")
Signed-off-by: Liu Shixin <liushixin2@...wei.com>
---
arch/riscv/kernel/stacktrace.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 08d11a53f39e..5fe2ae4cf135 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -30,6 +30,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
fp = (unsigned long)__builtin_frame_address(0);
sp = current_stack_pointer;
pc = (unsigned long)walk_stackframe;
+ level = -1;
} else {
/* task blocked in __switch_to */
fp = task->thread.s[0];
@@ -41,7 +42,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
unsigned long low, high;
struct stackframe *frame;
- if (unlikely(!__kernel_text_address(pc) || (level++ >= 1 && !fn(arg, pc))))
+ if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
break;
/* Validate frame pointer */
--
2.25.1
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