From: Liu Shixin <liushixin2@xxxxxxxxxx>
[ Upstream commit cb80242cc679d6397e77d8a964deeb3ff218d2b5 ]
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. Commit 6a00ef449370 ("riscv: eliminate
unreliable __builtin_frame_address(1)") 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: 6a00ef449370 ("riscv: eliminate unreliable __builtin_frame_address(1)")
Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
Tested-by: Samuel Holland <samuel@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221207025038.1022045-1-liushixin2@xxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 811e837a8c4ee..ee8ef91c8aaf4 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -32,6 +32,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
fp = (unsigned long)__builtin_frame_address(0);
sp = sp_in_global;
pc = (unsigned long)walk_stackframe;
+ level = -1;
} else {
/* task blocked in __switch_to */
fp = task->thread.s[0];
@@ -43,7 +44,7 @@ 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 */
--
2.39.0
