selftests/x86: Add a fork() to entry_from_vm86 to catch fork bugs

Mere possession of vm86 state is strange.  Make sure that nothing
gets corrupted if we fork after calling vm86().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Stas Sergeev <stsp@list.ru>
Link: http://lkml.kernel.org/r/08f83295460a80e41dc5e3e81ec40d6844d316f5.1446270067.git.luto@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/tools/testing/selftests/x86/entry_from_vm86.c b/tools/testing/selftests/x86/entry_from_vm86.c
index 421c607a8856887d0f9f6048c2ab26bd9367efdd..d075ea0e5ca1ac0a42ce0d48e25b30a1a059de48 100644 (file)
--- a/tools/testing/selftests/x86/entry_from_vm86.c
+++ b/tools/testing/selftests/x86/entry_from_vm86.c
@@ -230,5 +230,9 @@ int main(void)
        }
        clearhandler(SIGSEGV);
 
+       /* Make sure nothing explodes if we fork. */
+       if (fork() > 0)
+               return 0;
+
        return (nerrs == 0 ? 0 : 1);
 }