[PATCH 5.6 038/254] selftests/x86/ptrace_syscall_32: Fix no-vDSO segfault

[Greg Kroah-Hartman]

From: Andy Lutomirski <luto@xxxxxxxxxx>

[ Upstream commit 630b99ab60aa972052a4202a1ff96c7e45eb0054 ]

If AT_SYSINFO is not present, don't try to call a NULL pointer.

Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/faaf688265a7e1a5b944d6f8bc0f6368158306d3.1584052409.git.luto@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/testing/selftests/x86/ptrace_syscall.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
index 6f22238f32173..12aaa063196e7 100644
--- a/tools/testing/selftests/x86/ptrace_syscall.c
+++ b/tools/testing/selftests/x86/ptrace_syscall.c
@@ -414,8 +414,12 @@ int main()
 
 #if defined(__i386__) && (!defined(__GLIBC__) || __GLIBC__ > 2 || __GLIBC_MINOR__ >= 16)
 	vsyscall32 = (void *)getauxval(AT_SYSINFO);
-	printf("[RUN]\tCheck AT_SYSINFO return regs\n");
-	test_sys32_regs(do_full_vsyscall32);
+	if (vsyscall32) {
+		printf("[RUN]\tCheck AT_SYSINFO return regs\n");
+		test_sys32_regs(do_full_vsyscall32);
+	} else {
+		printf("[SKIP]\tAT_SYSINFO is not available\n");
+	}
 #endif
 
 	test_ptrace_syscall_restart();
-- 
2.20.1