[PATCH v6 06/39] kmsan: Fix kmsan_copy_to_user() on arches with overlapping address spaces

[Ilya Leoshkevich]

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.

Reported-by: Alexander Gordeev <agord...@linux.ibm.com>
Reviewed-by: Alexander Potapenko <gli...@google.com>
Signed-off-by: Ilya Leoshkevich <i...@linux.ibm.com>
---
 mm/kmsan/hooks.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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);
-- 
2.45.1