Directly calling do_exit with a signal number has the problem that
all of the side effects of the signal don't happen, such as
killing all of the threads of a process instead of just the
calling thread.

So replace do_exit(SIGSYS) with force_fatal_sig(SIGSYS) which
causes the signal handling to take it's normal path and work
as expected.

Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: "Eric W. Biederman" <redacted>
---
 arch/x86/entry/vsyscall/vsyscall_64.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index 1b40b9297083..0b6b277ee050 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c

@@ -226,7 +226,8 @@ bool emulate_vsyscall(unsigned long error_code,
 	if ((!tmp && regs->orig_ax != syscall_nr) || regs->ip != address) {
 		warn_bad_vsyscall(KERN_DEBUG, regs,
 				  "seccomp tried to change syscall nr or ip");
-		do_exit(SIGSYS);
+		force_fatal_sig(SIGSYS);
+		return true;
 	}
 	regs->orig_ax = -1;
 	if (tmp)