In current kernel, hugetlb_no_page() calls folio_zero_user() with the
fault address. Where the fault address may be not aligned with the huge
page size. Then, folio_zero_user() may call clear_gigantic_page() with
the address, while clear_gigantic_page() requires the address to be huge
page size aligned. So, this may cause memory corruption or information
leak, addtional, use more obvious naming 'addr_hint' instead of 'addr'
for clear_gigantic_page().
Fixes: 78fefd04c123 ("mm: memory: convert clear_huge_page() to folio_zero_user()")
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
v3:
- revise patch description, suggested by Huang Ying
- use addr_hint for clear_gigantic_page(), suggested by David
v2:
- update changelog to clarify the impact, per Andrew
fs/hugetlbfs/inode.c | 2 +-
mm/memory.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index a4441fb77f7c..a5ea006f403e 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -825,7 +825,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
error = PTR_ERR(folio);
goto out;
}
- folio_zero_user(folio, ALIGN_DOWN(addr, hpage_size));
+ folio_zero_user(folio, addr);
__folio_mark_uptodate(folio);
error = hugetlb_add_to_page_cache(folio, mapping, index);
if (unlikely(error)) {
diff --git a/mm/memory.c b/mm/memory.c
index 75c2dfd04f72..84864387f965 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6815,9 +6815,10 @@ static inline int process_huge_page(
return 0;
}
-static void clear_gigantic_page(struct folio *folio, unsigned long addr,
+static void clear_gigantic_page(struct folio *folio, unsigned long addr_hint,
unsigned int nr_pages)
{
+ unsigned long addr = ALIGN_DOWN(addr_hint, folio_size(folio));
int i;
might_sleep();
--
2.27.0
