[PATCH] mm/zsmalloc: copy KMSAN metadata in zs_page_migrate()

[Shigeru Yoshida <syoshida@redhat.com>]

zs_page_migrate() uses copy_page() to copy the contents of a zspage
page during migration. However, copy_page() is not instrumented by
KMSAN, so the shadow and origin metadata of the destination page are
not updated.

As a result, subsequent accesses to the migrated page are reported
as use-after-free by KMSAN, despite the data being correctly copied.

Add a kmsan_copy_page_meta() call after copy_page() to propagate the
KMSAN metadata to the new page, matching what copy_highpage() does
internally.

Fixes: afb2d666d025 ("zsmalloc: use copy_page for full page copy")
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
---
 mm/zsmalloc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 2c1430bf8d57..79ef9d57f2e1 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1741,6 +1741,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	 */
 	d_addr = kmap_local_zpdesc(newzpdesc);
 	copy_page(d_addr, s_addr);
+	kmsan_copy_page_meta(zpdesc_page(newzpdesc), zpdesc_page(zpdesc));
 	kunmap_local(d_addr);
 
 	for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE;
-- 
2.52.0