linux-kernel - [PATCH] selftests: x86: fix [-Wstringop-overread] warn in test_process_vm

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Date:   Thu, 21 Oct 2021 15:33:33 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     shuah@...nel.org
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] selftests: x86: fix [-Wstringop-overread] warn in test_process_vm_readv()

Fix the following [-Wstringop-overread] by passing in the variable
instead of the value.

test_vsyscall.c: In function ‘test_process_vm_readv’:
test_vsyscall.c:500:22: warning: ‘__builtin_memcmp_eq’ specified bound 4096 exceeds source size 0 [-Wstringop-overread]
  500 |                 if (!memcmp(buf, (const void *)0xffffffffff600000, 4096)) {
      |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
---
 tools/testing/selftests/x86/test_vsyscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c
index 65c141ebfbbd..5b45e6986aea 100644
--- a/tools/testing/selftests/x86/test_vsyscall.c
+++ b/tools/testing/selftests/x86/test_vsyscall.c
@@ -497,7 +497,7 @@ static int test_process_vm_readv(void)
 	}
 
 	if (vsyscall_map_r) {
-		if (!memcmp(buf, (const void *)0xffffffffff600000, 4096)) {
+		if (!memcmp(buf, remote.iov_base, sizeof(buf))) {
 			printf("[OK]\tIt worked and read correct data\n");
 		} else {
 			printf("[FAIL]\tIt worked but returned incorrect data\n");
-- 
2.32.0