From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3wRT6M30q6zDqZf for ; Tue, 16 May 2017 04:06:19 +1000 (AEST) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v4FI03mF118023 for ; Mon, 15 May 2017 14:06:11 -0400 Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) by mx0a-001b2d01.pphosted.com with ESMTP id 2afb6pbrs4-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 15 May 2017 14:06:10 -0400 Received: from localhost by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 16 May 2017 04:06:08 +1000 Received: from d23av05.au.ibm.com (d23av05.au.ibm.com [9.190.234.119]) by d23relay10.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v4FI5vw16947162 for ; Tue, 16 May 2017 04:06:05 +1000 Received: from d23av05.au.ibm.com (localhost [127.0.0.1]) by d23av05.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v4FI5WRY020835 for ; Tue, 16 May 2017 04:05:33 +1000 From: "Naveen N. Rao" To: Michael Ellerman Cc: Ananth N Mavinakayanahalli , Masami Hiramatsu , linuxppc-dev@lists.ozlabs.org Subject: [PATCH 2/2] powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return() Date: Mon, 15 May 2017 23:35:04 +0530 In-Reply-To: <0572aa31dd57bef6f158ac97d0b666a0c545356a.1494871248.git.naveen.n.rao@linux.vnet.ibm.com> References: <0572aa31dd57bef6f158ac97d0b666a0c545356a.1494871248.git.naveen.n.rao@linux.vnet.ibm.com> In-Reply-To: <0572aa31dd57bef6f158ac97d0b666a0c545356a.1494871248.git.naveen.n.rao@linux.vnet.ibm.com> References: <0572aa31dd57bef6f158ac97d0b666a0c545356a.1494871248.git.naveen.n.rao@linux.vnet.ibm.com> Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Fix a circa 2005 FIXME by implementing a check to ensure that we actually got into the jprobe break handler() due to the trap in jprobe_return(). Signed-off-by: Naveen N. Rao --- arch/powerpc/kernel/kprobes.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 19b053475758..1ebeb8c482db 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -627,25 +627,23 @@ NOKPROBE_SYMBOL(setjmp_pre_handler); void __used jprobe_return(void) { - asm volatile("trap" ::: "memory"); + asm volatile("jprobe_return_trap:\n" + "trap\n" + ::: "memory"); } NOKPROBE_SYMBOL(jprobe_return); -static void __used jprobe_return_end(void) -{ -} -NOKPROBE_SYMBOL(jprobe_return_end); - int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); unsigned long sp; - /* - * FIXME - we should ideally be validating that we got here 'cos - * of the "trap" in jprobe_return() above, before restoring the - * saved regs... - */ + if (regs->nip != ppc_kallsyms_lookup_name("jprobe_return_trap")) { + WARN(1, "longjmp_break_handler NIP (0x%lx) does not match jprobe_return_trap (0x%lx)\n", + regs->nip, ppc_kallsyms_lookup_name("jprobe_return_trap")); + return 0; + } + memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); sp = kernel_stack_pointer(regs); memcpy((void *)sp, &kcb->jprobes_stack, MIN_STACK_SIZE(sp)); -- 2.12.2