selftests/x86/ptrace_syscall_32: Fix no-vDSO segfault

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

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/faaf688265a7e1a5b944d6f8bc0f6368158306d3.1584052409.git.luto@kernel.org

diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
index 6f22238..12aaa06 100644 (file)
--- 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();