kmsan: fix kmsan_copy_to_user() on arches with overlapping address spaces

Comparing pointers with TASK_SIZE does not make sense when kernel and
userspace overlap.  Assume that we are handling user memory access in this
case.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ilya Leoshkevich <[email protected]>
Reported-by: Alexander Gordeev <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 22e8657800ef..b408714f9ba3 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -267,7 +267,8 @@ void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
 		return;
 
 	ua_flags = user_access_save();
-	if ((u64)to < TASK_SIZE) {
+	if (!IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) ||
+	    (u64)to < TASK_SIZE) {
 		/* This is a user memory access, check it. */
 		kmsan_internal_check_memory((void *)from, to_copy - left, to,
 					    REASON_COPY_TO_USER);