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From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
To:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kasan-dev@googlegroups.com
Cc:     Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Subject: [PATCH v15 4/8] kasan: Add report for async mode
Date:   Fri, 12 Mar 2021 14:22:06 +0000
Message-Id: <20210312142210.21326-5-vincenzo.frascino@arm.com>
In-Reply-To: <20210312142210.21326-1-vincenzo.frascino@arm.com>
References: <20210312142210.21326-1-vincenzo.frascino@arm.com>
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KASAN provides an asynchronous mode of execution.

Add reporting functionality for this mode.

Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 include/linux/kasan.h |  6 ++++++
 mm/kasan/kasan.h      | 16 ++++++++++++++++
 mm/kasan/report.c     | 17 ++++++++++++++++-
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 44c147dae7e3..9f5faefd1744 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -377,6 +377,12 @@ static inline void *kasan_reset_tag(const void *addr)
 
 #endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS*/
 
+#ifdef CONFIG_KASAN_HW_TAGS
+
+void kasan_report_async(void);
+
+#endif /* CONFIG_KASAN_HW_TAGS */
+
 #ifdef CONFIG_KASAN_SW_TAGS
 void __init kasan_init_sw_tags(void);
 #else
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 265ad35a04ad..02957cec1a61 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -7,17 +7,33 @@
 #include <linux/stackdepot.h>
 
 #ifdef CONFIG_KASAN_HW_TAGS
+
 #include <linux/static_key.h>
+
 DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
+extern bool kasan_flag_async __ro_after_init;
+
 static inline bool kasan_stack_collection_enabled(void)
 {
 	return static_branch_unlikely(&kasan_flag_stacktrace);
 }
+
+static inline bool kasan_async_mode_enabled(void)
+{
+	return kasan_flag_async;
+}
 #else
+
 static inline bool kasan_stack_collection_enabled(void)
 {
 	return true;
 }
+
+static inline bool kasan_async_mode_enabled(void)
+{
+	return false;
+}
+
 #endif
 
 extern bool kasan_flag_panic __ro_after_init;
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 87b271206163..8b0843a2cdd7 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -87,7 +87,8 @@ static void start_report(unsigned long *flags)
 
 static void end_report(unsigned long *flags, unsigned long addr)
 {
-	trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
+	if (!kasan_async_mode_enabled())
+		trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
 	pr_err("==================================================================\n");
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irqrestore(&report_lock, *flags);
@@ -360,6 +361,20 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
 	end_report(&flags, (unsigned long)object);
 }
 
+#ifdef CONFIG_KASAN_HW_TAGS
+void kasan_report_async(void)
+{
+	unsigned long flags;
+
+	start_report(&flags);
+	pr_err("BUG: KASAN: invalid-access\n");
+	pr_err("Asynchronous mode enabled: no access details available\n");
+	pr_err("\n");
+	dump_stack();
+	end_report(&flags, 0);
+}
+#endif /* CONFIG_KASAN_HW_TAGS */
+
 static void __kasan_report(unsigned long addr, size_t size, bool is_write,
 				unsigned long ip)
 {
-- 
2.30.0