From: Liu Shixin liushixin2@huawei.com
[ 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@huawei.com Tested-by: Samuel Holland samuel@sholland.org Link: https://lore.kernel.org/r/20221207025038.1022045-1-liushixin2@huawei.com Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 bcfe9eb55f80f..85cd5442d2f81 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 */