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[mm,v4,21/39] kasan, vmalloc: reset tags in vmalloc functions

Message ID e31d392c5eca9db6f45ca6b320a929ecd53f787c.1640036051.git.andreyknvl@google.com (mailing list archive)
State New, archived
Headers show
Series kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS | expand

Commit Message

andrey.konovalov@linux.dev Dec. 20, 2021, 9:59 p.m. UTC 
From: Andrey Konovalov <andreyknvl@google.com>

In preparation for adding vmalloc support to SW/HW_TAGS KASAN,
reset pointer tags in functions that use pointer values in
range checks.

vread() is a special case here. Despite the untagging of the addr
pointer in its prologue, the accesses performed by vread() are checked.

Instead of accessing the virtual mappings though addr directly, vread()
recovers the physical address via page_address(vmalloc_to_page()) and
acceses that. And as page_address() recovers the pointer tag, the
accesses get checked.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

---

Changes v1->v2:
- Clarified the description of untagging in vread().
---
 mm/vmalloc.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 10011a07231d..eaacdf3abfa7 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -73,7 +73,7 @@  static const bool vmap_allow_huge = false;
 
 bool is_vmalloc_addr(const void *x)
 {
-	unsigned long addr = (unsigned long)x;
+	unsigned long addr = (unsigned long)kasan_reset_tag(x);
 
 	return addr >= VMALLOC_START && addr < VMALLOC_END;
 }
@@ -631,7 +631,7 @@  int is_vmalloc_or_module_addr(const void *x)
 	 * just put it in the vmalloc space.
 	 */
 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
-	unsigned long addr = (unsigned long)x;
+	unsigned long addr = (unsigned long)kasan_reset_tag(x);
 	if (addr >= MODULES_VADDR && addr < MODULES_END)
 		return 1;
 #endif
@@ -805,6 +805,8 @@  static struct vmap_area *find_vmap_area_exceed_addr(unsigned long addr)
 	struct vmap_area *va = NULL;
 	struct rb_node *n = vmap_area_root.rb_node;
 
+	addr = (unsigned long)kasan_reset_tag((void *)addr);
+
 	while (n) {
 		struct vmap_area *tmp;
 
@@ -826,6 +828,8 @@  static struct vmap_area *__find_vmap_area(unsigned long addr)
 {
 	struct rb_node *n = vmap_area_root.rb_node;
 
+	addr = (unsigned long)kasan_reset_tag((void *)addr);
+
 	while (n) {
 		struct vmap_area *va;
 
@@ -2144,7 +2148,7 @@  EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 void vm_unmap_ram(const void *mem, unsigned int count)
 {
 	unsigned long size = (unsigned long)count << PAGE_SHIFT;
-	unsigned long addr = (unsigned long)mem;
+	unsigned long addr = (unsigned long)kasan_reset_tag(mem);
 	struct vmap_area *va;
 
 	might_sleep();
@@ -3406,6 +3410,8 @@  long vread(char *buf, char *addr, unsigned long count)
 	unsigned long buflen = count;
 	unsigned long n;
 
+	addr = kasan_reset_tag(addr);
+
 	/* Don't allow overflow */
 	if ((unsigned long) addr + count < count)
 		count = -(unsigned long) addr;