The buffer pointer "line" is not initialized. This pointer is passed to
getline().

It can still work if the stack is zero-initialized, because getline() can
work with a NULL pointer as buffer.

But this is obviously broken. This bug shows up while running the test on a
riscv64 machine.

Fix it by properly initializing the pointer.

Fixes: 15858da53542 ("selftests: coredump: Add stackdump test")
Signed-off-by: Nam Cao <namcao@linutronix.de>
---
 tools/testing/selftests/coredump/stackdump_test.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c
index 137b2364a082..c23cf95c3f6d 100644
--- a/tools/testing/selftests/coredump/stackdump_test.c
+++ b/tools/testing/selftests/coredump/stackdump_test.c
@@ -138,10 +138,12 @@ TEST_F(coredump, stackdump)
 	ASSERT_NE(file, NULL);
 
 	/* Step 4: Make sure all stack pointer values are non-zero */
+	line = NULL;
 	for (i = 0; -1 != getline(&line, &line_length, file); ++i) {
 		stack = strtoull(line, NULL, 10);
 		ASSERT_NE(stack, 0);
 	}
+	free(line);
 
 	ASSERT_EQ(i, 1 + NUM_THREAD_SPAWN);
 
-- 
2.39.5

On 11-04-2025 20:39, Nam Cao wrote:
>   	/* Step 4: Make sure all stack pointer values are non-zero */
> +	line = NULL;

such case it should initialize at declaration time.
better to move up char *test_dir, *line = NULL;

>   	for (i = 0; -1 != getline(&line, &line_length, file); ++i) {
>   		stack = strtoull(line, NULL, 10);
>   		ASSERT_NE(stack, 0);
>   	}


Thanks,
Alok