linux-kernel - [PATCH V2 3/3] perf/x86/intel/uncore: Validate MMIO address before accessing

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Date:   Thu, 28 May 2020 06:15:27 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     ak@...ux.intel.com, David.Laight@...LAB.COM,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V2 3/3] perf/x86/intel/uncore: Validate MMIO address before accessing

From: Kan Liang <kan.liang@...ux.intel.com>

An oops will be triggered, if perf tries to access an invalid address
which exceeds the mapped area.

Check the address before the actual access to MMIO sapce of an uncore
unit.

Suggested-by: David Laight <David.Laight@...LAB.COM>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/intel/uncore.c       |  3 +++
 arch/x86/events/intel/uncore.h       | 12 ++++++++++++
 arch/x86/events/intel/uncore_snbep.c |  6 ++++++
 3 files changed, 21 insertions(+)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index cf76d66..284f8e7 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -132,6 +132,9 @@ u64 uncore_mmio_read_counter(struct intel_uncore_box *box,
 	if (!box->io_addr)
 		return 0;
 
+	if (!is_valid_mmio_offset(box, event->hw.event_base))
+		return 0;
+
 	return readq(box->io_addr + event->hw.event_base);
 }
 
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index c2e5725..672e9e1 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -197,6 +197,18 @@ static inline bool uncore_pmc_freerunning(int idx)
 	return idx == UNCORE_PMC_IDX_FREERUNNING;
 }
 
+static inline bool is_valid_mmio_offset(struct intel_uncore_box *box,
+					unsigned long offset)
+{
+	if (box->pmu->type->mmio_map_size > offset)
+		return true;
+
+	pr_warn_once("perf uncore: Access invalid address of %s.\n",
+		     box->pmu->type->name);
+
+	return false;
+}
+
 static inline
 unsigned int uncore_mmio_box_ctl(struct intel_uncore_box *box)
 {
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 801b662..9c7a641 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4487,6 +4487,9 @@ static void snr_uncore_mmio_enable_event(struct intel_uncore_box *box,
 	if (!box->io_addr)
 		return;
 
+	if (!is_valid_mmio_offset(box, hwc->config_base))
+		return;
+
 	writel(hwc->config | SNBEP_PMON_CTL_EN,
 	       box->io_addr + hwc->config_base);
 }
@@ -4499,6 +4502,9 @@ static void snr_uncore_mmio_disable_event(struct intel_uncore_box *box,
 	if (!box->io_addr)
 		return;
 
+	if (!is_valid_mmio_offset(box, hwc->config_base))
+		return;
+
 	writel(hwc->config, box->io_addr + hwc->config_base);
 }
 
-- 
2.7.4