[PATCH v4 3/5] kasan: Add report for async mode

[Vincenzo Frascino]

KASAN provides an asynchronous mode of execution.

Add reporting functionality for this mode.

Cc: Dmitry Vyukov <dvyukov at google.com>
Cc: Andrey Ryabinin <aryabinin at virtuozzo.com>
Cc: Alexander Potapenko <glider at google.com>
Cc: Andrey Konovalov <andreyknvl at google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino at arm.com>
---
 include/linux/kasan.h |  3 +++
 mm/kasan/report.c     | 16 ++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index fe1ae73ff8b5..8f43836ccdac 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -336,6 +336,9 @@ static inline void *kasan_reset_tag(const void *addr)
 bool kasan_report(unsigned long addr, size_t size,
 		bool is_write, unsigned long ip);
 
+bool kasan_report_async(unsigned long addr, size_t size,
+			bool is_write, unsigned long ip);
+
 #else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
 
 static inline void *kasan_reset_tag(const void *addr)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index c0fb21797550..946016ead6a9 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -388,11 +388,11 @@ static void __kasan_report(unsigned long addr, size_t size, bool is_write,
 	start_report(&flags);
 
 	print_error_description(&info);
-	if (addr_has_metadata(untagged_addr))
+	if (addr_has_metadata(untagged_addr) && (untagged_addr != 0))
 		print_tags(get_tag(tagged_addr), info.first_bad_addr);
 	pr_err("\n");
 
-	if (addr_has_metadata(untagged_addr)) {
+	if (addr_has_metadata(untagged_addr) && (untagged_addr != 0)) {
 		print_address_description(untagged_addr, get_tag(tagged_addr));
 		pr_err("\n");
 		print_memory_metadata(info.first_bad_addr);
@@ -419,6 +419,18 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
 	return ret;
 }
 
+bool kasan_report_async(unsigned long addr, size_t size,
+			bool is_write, unsigned long ip)
+{
+	pr_info("==================================================================\n");
+	pr_info("KASAN: set in asynchronous mode\n");
+	pr_info("KASAN: some information might not be accurate\n");
+	pr_info("KASAN: fault address is ignored\n");
+	pr_info("KASAN: write/read distinction is ignored\n");
+
+	return kasan_report(addr, size, is_write, ip);
+}
+
 #ifdef CONFIG_KASAN_INLINE
 /*
  * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
-- 
2.30.0