From b3f0b1f694258b3b3debc5256eec94bb2a9eb454 Mon Sep 17 00:00:00 2001 From: Swetha Chikkaboraiah Date: Wed, 27 Jan 2016 11:46:54 +0530 Subject: [PATCH] msm: perf: Protect buffer overflow due to malicious user In function krait_pmu_disable_event, parameter hwc comes from userspace and is untrusted.The function krait_clearpmu is called after the function get_krait_evtinfo. Function get_krait_evtinfo as parameter krait_evt_type variable which is used to extract the groupcode(reg) which is bound to KRAIT_MAX_L1_REG (is 3). After validation,one code path modifies groupcode(reg):If this code path executes, groupcode(reg) can be 3,4, 5, or 6. In krait_clearpmu groupcode used to access array krait_functions whose size is 3. Since groupcode can be 3,4,5,6 accessing array krait_functions lead to bufferoverlflow. This change will validate groupcode not to exceed 3. CVE-2016-0805 Bug:ANDROID-25773204 Change-Id: I48c92adda137d8a074b4e1a367a468195a810ca1 CRs-fixed: 962450 Signed-off-by: Swetha Chikkaboraiah Signed-off-by: Karthik Jadala --- arch/arm/kernel/perf_event_msm_krait.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/arm/kernel/perf_event_msm_krait.c b/arch/arm/kernel/perf_event_msm_krait.c index 49aae5a66b650..34f9b4e5b099d 100644 --- a/arch/arm/kernel/perf_event_msm_krait.c +++ b/arch/arm/kernel/perf_event_msm_krait.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2011-2014, The Linux Foundation. All rights reserved. + * Copyright (c) 2011-2014, 2016 The Linux Foundation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and @@ -208,9 +208,6 @@ static unsigned int get_krait_evtinfo(unsigned int krait_evt_type, code = (krait_evt_type & 0x00FF0) >> 4; group = krait_evt_type & 0x0000F; - if ((group > 3) || (reg > KRAIT_MAX_L1_REG)) - return -EINVAL; - if (prefix != KRAIT_EVT_PREFIX && prefix != KRAIT_VENUMEVT_PREFIX) return -EINVAL; @@ -221,6 +218,9 @@ static unsigned int get_krait_evtinfo(unsigned int krait_evt_type, reg += VENUM_BASE_OFFSET; } + if ((group > 3) || (reg > KRAIT_MAX_L1_REG)) + return -EINVAL; + evtinfo->group_setval = 0x80000000 | (code << (group * 8)); evtinfo->groupcode = reg; evtinfo->armv7_evt_type = evt_type_base[reg] | group;