[patch 15/18] kasan: make addr_has_metadata() return true for valid addresses

From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Subject: kasan: make addr_has_metadata() return true for valid addresses

Currently, addr_has_metadata() returns true for every address.  An invalid
address (e.g.  NULL) passed to the function when, KASAN_HW_TAGS is
enabled, leads to a kernel panic.

Make addr_has_metadata() return true for valid addresses only.

Note: KASAN_HW_TAGS support for vmalloc will be added with a future patch.

Link: https://lkml.kernel.org/r/20210126134409.47894-3-vincenzo.frascino@arm.com
Fixes: 2e903b91479782b7 ("kasan, arm64: implement HW_TAGS runtime")
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Andrey Konovalov <redacted>
Cc: Andrey Ryabinin <redacted>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Leon Romanovsky <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Naresh Kamboju <redacted>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kasan/kasan.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/kasan/kasan.h~kasan-make-addr_has_metadata-return-true-for-valid-addresses
+++ a/mm/kasan/kasan.h

@@ -209,7 +209,7 @@ bool check_memory_region(unsigned long a
 
 static inline bool addr_has_metadata(const void *addr)
 {
-	return true;
+	return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
 }
 
 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */

_