Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752626AbbGaDdU (ORCPT ); Thu, 30 Jul 2015 23:33:20 -0400 Received: from mail.kernel.org ([198.145.29.136]:45692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752302AbbGaDcs (ORCPT ); Thu, 30 Jul 2015 23:32:48 -0400 From: Andy Lutomirski To: Peter Zijlstra , linux-kernel@vger.kernel.org Cc: Brian Gerst , Steven Rostedt , Borislav Petkov , Thomas Gleixner , Linus Torvalds , X86 ML , Masami Hiramatsu , Andy Lutomirski Subject: [PATCH 2/3] x86/perf/hw_breakpoint: Improve range breakpoint validation Date: Thu, 30 Jul 2015 20:32:41 -0700 Message-Id: X-Mailer: git-send-email 2.4.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1389 Lines: 40 Range breakpoints will do the wrong thing if the address isn't aligned. While we're there, add comments about why it's safe for instruction breakpoints. Signed-off-by: Andy Lutomirski --- arch/x86/kernel/hw_breakpoint.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index 78f3e90c5659..6f345d302cf6 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -291,8 +291,18 @@ static int arch_build_bp_info(struct perf_event *bp) break; #endif default: + /* AMD range breakpoint */ if (!is_power_of_2(bp->attr.bp_len)) return -EINVAL; + if (bp->attr.bp_addr & (bp->attr.bp_len - 1)) + return -EINVAL; + /* + * It's impossible to use a range breakpoint to fake out + * user vs kernel detection because bp_len - 1 can't + * have the high bit set. If we ever allow range instruction + * breakpoints, then we'll have to check for kprobe-blacklisted + * addresses anywhere in the range. + */ if (!cpu_has_bpext) return -EOPNOTSUPP; info->mask = bp->attr.bp_len - 1; -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/