[PATCH 2/2] test: self: free a zero-sized buffer with free_sensitive()

[Ahmad Fatoum]

free_sensitive() asks the allocator for the usable size of the buffer
before zeroing it, so it is one more path that has to cope with the
ZERO_SIZE_PTR that zero-sized allocations return. The sandbox got this
wrong until the previous commit and only ASAN noticed, so let's have the
allocator selftest walk over it.

Assisted-by: Claude:opus-5-1m
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 test/self/malloc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/test/self/malloc.c b/test/self/malloc.c
index 1ec351c3efe5..14d936f96a45 100644
--- a/test/self/malloc.c
+++ b/test/self/malloc.c
@@ -140,6 +140,11 @@ static void test_malloc(void)
 	__expect_cond(p == ZERO_SIZE_PTR, true, "get ZERO_SIZE_PTR for 0-size buffers", __func__, __LINE__);
 
 	free(p);
-	free(tmp);
+
+	/*
+	 * free_sensitive() asks the allocator for the usable size before it
+	 * zeroes the buffer, so ZERO_SIZE_PTR has to survive that path too
+	 */
+	free_sensitive(tmp);
 }
 bselftest(core, test_malloc);
-- 
2.47.3