1 files changed, 13 insertions, 2 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 34a1c3e46ed7..ecc97f74ab18 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -287,10 +287,21 @@ struct page *vmalloc_to_page(const void *vmalloc_addr)
 	if (p4d_none(*p4d))
 		return NULL;
 	pud = pud_offset(p4d, addr);
-	if (pud_none(*pud))
+
+	/*
+	 * Don't dereference bad PUD or PMD (below) entries. This will also
+	 * identify huge mappings, which we may encounter on architectures
+	 * that define CONFIG_HAVE_ARCH_HUGE_VMAP=y. Such regions will be
+	 * identified as vmalloc addresses by is_vmalloc_addr(), but are
+	 * not [unambiguously] associated with a struct page, so there is
+	 * no correct value to return for them.
+	 */
+	WARN_ON_ONCE(pud_bad(*pud));
+	if (pud_none(*pud) || pud_bad(*pud))
 		return NULL;
 	pmd = pmd_offset(pud, addr);
-	if (pmd_none(*pmd))
+	WARN_ON_ONCE(pmd_bad(*pmd));
+	if (pmd_none(*pmd) || pmd_bad(*pmd))
 		return NULL;
 
 	ptep = pte_offset_map(pmd, addr);