From fd815c0b8dad8a7d9d74bfc09217943bda0f03a9 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Wed, 9 Jul 2014 21:39:40 +0000 Subject: [PATCH] For safety, ensure that any consumer of the set_regs() and ptrace_set_pc() use the correct return to userspace using iret. The signal return, PT_CONTINUE (which in fact uses signal return path) set the pcb flag already. The setcontext(2) enforces iret return when %rip is incorrect. Due to this, the change is redundand, but is made to ensure that no path which modifies context, forgets to set PCB_FULL_IRET. Inspired by: CVE-2014-4699 Reviewed by: jhb Sponsored by: The FreeBSD Foundation MFC after: 1 week --- sys/amd64/amd64/machdep.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c index 82c2c89b777..5afd58cd685 100644 --- a/sys/amd64/amd64/machdep.c +++ b/sys/amd64/amd64/machdep.c @@ -2144,7 +2144,9 @@ makectx(struct trapframe *tf, struct pcb *pcb) int ptrace_set_pc(struct thread *td, unsigned long addr) { + td->td_frame->tf_rip = addr; + set_pcb_flags(td->td_pcb, PCB_FULL_IRET); return (0); } @@ -2244,8 +2246,8 @@ set_regs(struct thread *td, struct reg *regs) tp->tf_fs = regs->r_fs; tp->tf_gs = regs->r_gs; tp->tf_flags = TF_HASSEGS; - set_pcb_flags(td->td_pcb, PCB_FULL_IRET); } + set_pcb_flags(td->td_pcb, PCB_FULL_IRET); return (0); }