[PATCH 6.12.y] mm/zsmalloc: copy KMSAN metadata in zs_page_migrate()

[Sasha Levin <sashal@kernel.org>]

From: Shigeru Yoshida <syoshida@redhat.com>

[ Upstream commit 4fb61d95ad21c3b6f1c09f357ff49d70abb0535e ]

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.

Link: https://lkml.kernel.org/r/20260321132912.93434-1-syoshida@redhat.com
Fixes: afb2d666d025 ("zsmalloc: use copy_page for full page copy")
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ translated zpdesc_page(newzpdesc/zpdesc) arguments to newpage/page ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/zsmalloc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index e4326af00e5eb..76adbce8d42b9 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1808,6 +1808,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	 */
 	d_addr = kmap_atomic(newpage);
 	copy_page(d_addr, s_addr);
+	kmsan_copy_page_meta(newpage, page);
 	kunmap_atomic(d_addr);
 
 	for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE;
-- 
2.53.0