Re: [PATCH v2 06/11] selftests/mm: fix two -Wformat-security warnings in uffd builds

From: David Hildenbrand
Date: Mon Jun 05 2023 - 07:38:10 EST


On 03.06.23 04:15, John Hubbard wrote:
The uffd tests generate two compile time warnings from clang's
-Wformat-security setting. These trigger at the call sites for
uffd_test_start() and uffd_test_skip().

1) Fix the uffd_test_start() issue by removing the intermediate
test_name variable (thanks to David Hildenbrand for showing how to do
this).

2) Fix the uffd_test_skip() issue by observing that there is no need for
a macro and a variable args approach, because all callers of
uffd_test_skip() pass in a simple char* string, without any format
specifiers. So just change uffd_test_skip() into a regular C function.

Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
tools/testing/selftests/mm/uffd-unit-tests.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 269c86768a02..04d91f144d1c 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -109,12 +109,11 @@ static void uffd_test_pass(void)
ksft_inc_fail_cnt(); \
} while (0)
-#define uffd_test_skip(...) do { \
- printf("skipped [reason: "); \
- printf(__VA_ARGS__); \
- printf("]\n"); \
- ksft_inc_xskip_cnt(); \
- } while (0)
+static void uffd_test_skip(const char *message)
+{
+ printf("skipped [reason: %s]\n", message);
+ ksft_inc_xskip_cnt();
+}
/*
* Returns 1 if specific userfaultfd supported, 0 otherwise. Note, we'll
@@ -1149,7 +1148,6 @@ int main(int argc, char *argv[])
uffd_test_case_t *test;
mem_type_t *mem_type;
uffd_test_args_t args;
- char test_name[128];
const char *errmsg;
int has_uffd, opt;
int i, j;
@@ -1192,10 +1190,8 @@ int main(int argc, char *argv[])
mem_type = &mem_types[j];
if (!(test->mem_targets & mem_type->mem_flag))
continue;
- snprintf(test_name, sizeof(test_name),
- "%s on %s", test->name, mem_type->name);
- uffd_test_start(test_name);
+ uffd_test_start("%s on %s", test->name, mem_type->name);
if (!uffd_feature_supported(test)) {
uffd_test_skip("feature missing");
continue;

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb