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

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Date:   Mon, 19 Jun 2023 18:17:14 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        John Hubbard <jhubbard@...dia.com>,
        Peter Xu <peterx@...hat.com>
Subject: [PATCH v2 06/11] selftests/mm: fix two -Wformat-security warnings in uffd builds

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@...hat.com>
Cc: Peter Xu <peterx@...hat.com>
Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
 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;
-- 
2.40.1