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.
Change-Id: I48c92adda137d8a074b4e1a367a468195a810ca1
CRs-fixed: 962450
Signed-off-by: Swetha Chikkaboraiah <schikk@codeaurora.org>
diff --git a/arch/arm/kernel/perf_event_msm_krait.c b/arch/arm/kernel/perf_event_msm_krait.c
index 49aae5a..34f9b4e 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 @@
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 @@
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;
