[PATCH] vdso/datastore: Zero out newly allocated datastore pages

[Thomas Weißschuh]

The data pages need to be zeroed initially, as garbage data can break
the vDSO userspace logic.

Fixes: 05988dba1179 ("vdso/datastore: Allocate data pages dynamically")
Link: https://lore.kernel.org/lkml/aQjJNmwniQwwjeBR@xxxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
---
I messed up and dropped __GFP_ZERO again when switching from folio_alloc() to
alloc_pages() in v6 of "sparc64: vdso: Switch to the generic vDSO library"
Previously the missing __GFP_ZERO triggered boot-failures in -next, but
apparently with alloc_pages() we got "lucky" so far.

This could also be merged into the originally broken commit.
---
 lib/vdso/datastore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/vdso/datastore.c b/lib/vdso/datastore.c
index cf5d784a4a5a..55f1654624e0 100644
--- a/lib/vdso/datastore.c
+++ b/lib/vdso/datastore.c
@@ -42,7 +42,7 @@ void __init vdso_setup_data_pages(void)
 	 * Do not use folios. In time namespaces the pages are mapped in a different order
 	 * to userspace, which is not handled by the folio optimizations in finish_fault().
 	 */
-	pages = alloc_pages(GFP_KERNEL, order);
+	pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
 	if (!pages)
 		panic("Unable to allocate VDSO storage pages");
 

---
base-commit: 7138a8698a39e81eb153e05500823fff76d5b3bd
change-id: 20260409-vdso-datastore-zero-87f0d2d482d6

Best regards,
--  
Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>