1 files changed, 24 insertions, 67 deletions

diff --git a/mm/usercopy.c b/mm/usercopy.c
index 2c235d5c2364..baeacc735b83 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -17,6 +17,7 @@
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
 #include <linux/thread_info.h>
+#include <linux/vmalloc.h>
 #include <linux/atomic.h>
 #include <linux/jump_label.h>
 #include <asm/sections.h>
@@ -157,91 +158,47 @@ static inline void check_bogus_address(const unsigned long ptr, unsigned long n,
 		usercopy_abort("null address", NULL, to_user, ptr, n);
 }
 
-/* Checks for allocs that are marked in some way as spanning multiple pages. */
-static inline void check_page_span(const void *ptr, unsigned long n,
-				   struct page *page, bool to_user)
+static inline void check_heap_object(const void *ptr, unsigned long n,
+				     bool to_user)
 {
-#ifdef CONFIG_HARDENED_USERCOPY_PAGESPAN
-	const void *end = ptr + n - 1;
-	struct page *endpage;
-	bool is_reserved, is_cma;
+	struct folio *folio;
 
-	/*
-	 * Sometimes the kernel data regions are not marked Reserved (see
-	 * check below). And sometimes [_sdata,_edata) does not cover
-	 * rodata and/or bss, so check each range explicitly.
-	 */
+	if (is_kmap_addr(ptr)) {
+		unsigned long page_end = (unsigned long)ptr | (PAGE_SIZE - 1);
 
-	/* Allow reads of kernel rodata region (if not marked as Reserved). */
-	if (ptr >= (const void *)__start_rodata &&
-	    end <= (const void *)__end_rodata) {
-		if (!to_user)
-			usercopy_abort("rodata", NULL, to_user, 0, n);
+		if ((unsigned long)ptr + n - 1 > page_end)
+			usercopy_abort("kmap", NULL, to_user,
+					offset_in_page(ptr), n);
 		return;
 	}
 
-	/* Allow kernel data region (if not marked as Reserved). */
-	if (ptr >= (const void *)_sdata && end <= (const void *)_edata)
-		return;
+	if (is_vmalloc_addr(ptr)) {
+		struct vm_struct *area = find_vm_area(ptr);
+		unsigned long offset;
 
-	/* Allow kernel bss region (if not marked as Reserved). */
-	if (ptr >= (const void *)__bss_start &&
-	    end <= (const void *)__bss_stop)
-		return;
-
-	/* Is the object wholly within one base page? */
-	if (likely(((unsigned long)ptr & (unsigned long)PAGE_MASK) ==
-		   ((unsigned long)end & (unsigned long)PAGE_MASK)))
-		return;
+		if (!area) {
+			usercopy_abort("vmalloc", "no area", to_user, 0, n);
+			return;
+		}
 
-	/* Allow if fully inside the same compound (__GFP_COMP) page. */
-	endpage = virt_to_head_page(end);
-	if (likely(endpage == page))
+		offset = ptr - area->addr;
+		if (offset + n > get_vm_area_size(area))
+			usercopy_abort("vmalloc", NULL, to_user, offset, n);
 		return;
-
-	/*
-	 * Reject if range is entirely either Reserved (i.e. special or
-	 * device memory), or CMA. Otherwise, reject since the object spans
-	 * several independently allocated pages.
-	 */
-	is_reserved = PageReserved(page);
-	is_cma = is_migrate_cma_page(page);
-	if (!is_reserved && !is_cma)
-		usercopy_abort("spans multiple pages", NULL, to_user, 0, n);
-
-	for (ptr += PAGE_SIZE; ptr <= end; ptr += PAGE_SIZE) {
-		page = virt_to_head_page(ptr);
-		if (is_reserved && !PageReserved(page))
-			usercopy_abort("spans Reserved and non-Reserved pages",
-				       NULL, to_user, 0, n);
-		if (is_cma && !is_migrate_cma_page(page))
-			usercopy_abort("spans CMA and non-CMA pages", NULL,
-				       to_user, 0, n);
 	}
-#endif
-}
-
-static inline void check_heap_object(const void *ptr, unsigned long n,
-				     bool to_user)
-{
-	struct folio *folio;
 
 	if (!virt_addr_valid(ptr))
 		return;
 
-	/*
-	 * When CONFIG_HIGHMEM=y, kmap_to_page() will give either the
-	 * highmem page or fallback to virt_to_page(). The following
-	 * is effectively a highmem-aware virt_to_slab().
-	 */
-	folio = page_folio(kmap_to_page((void *)ptr));
+	folio = virt_to_folio(ptr);
 
 	if (folio_test_slab(folio)) {
 		/* Check slab allocator for flags and size. */
 		__check_heap_object(ptr, n, folio_slab(folio), to_user);
-	} else {
-		/* Verify object does not incorrectly span multiple pages. */
-		check_page_span(ptr, n, folio_page(folio, 0), to_user);
+	} else if (folio_test_large(folio)) {
+		unsigned long offset = ptr - folio_address(folio);
+		if (offset + n > folio_size(folio))
+			usercopy_abort("page alloc", NULL, to_user, offset, n);
 	}
 }