Misc hardening changes for 5.19-rc1

Hi Linus,
 
 Please, pull the following hardening changes that I've been collecting
 in my tree during the last development cycle. All of them have been
 baking in linux-next.
 
 Replace open-coded instances with size_t saturating arithmetic helpers:
 
 - virt: acrn: Prefer array_size and struct_size over open coded arithmetic (Len Baker)
 - afs: Prefer struct_size over open coded arithmetic (Len Baker)
 
 Thanks
 --
 Gustavo
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEkmRahXBSurMIg1YvRwW0y0cG2zEFAmKNUvYACgkQRwW0y0cG
 2zGm1g//YZYWBEzqOncd1K4/TBzbMytxE7oQYqUiS4e3V5D1eiT8924BLr7iuWMd
 c64Lv0trjyHCjdqBxGLMz5cv5EZd206xS3bqIQ8gqcKHOK/z7ob/c7YJxdUcXaWK
 oyGY65Arg9XnuRIJvNeiwdJNpPGsSyI8BSRC6gf6NFYke/GNIgv3rxmVBSbH8V7W
 QVBWf3AWR8+ZlXJFHWEfIAMRwFtumAhak3ZpN/4SDWM6cw3PIm1TFEO5Jx/rWaNn
 LZth+91uJU6UeSrhrME/QQ9Q1kgmLUMqzW3U/HpMky7Ugi0ffWIHc83XYDOgrFRJ
 Br5KLL4c5SHMJfPXqHMsbRNG/bI6fJfd2A0vUDIQMdy4kX88MAzTsUzSiGe6gAAc
 a3RQV4qUkBvC53glZm4pb0IGY4j3vO1tf6Hd9BdxH4knpfQzVNTAwHXUxDq8kDBu
 Bir3B60qAktszxdp/QukmfoTRpVPSV732TMgIllVPFtFD/KYCiYFhSILPouh5JWJ
 3TP8ND1hKrV3P9FVirlJxdFLcADu8dyrmwxKdxZVa6ek9xtr0gt111FYcTeZG+eS
 PaJ7N8G+OkvYktv14/+0DBgIQdeHQ/kp6D4eTjQZ6y0k0b7uAI3HRv7fxWh8eyOw
 RmaE8jQCHokUnerouBUIGEwAmyFhN3atogqIHczB4ebBNbEeOGg=
 =22O8
 -----END PGP SIGNATURE-----

Merge tag 'size_t-saturating-helpers-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull misc hardening updates from Gustavo Silva:
 "Replace a few open-coded instances with size_t saturating arithmetic
  helpers"

* tag 'size_t-saturating-helpers-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux:
  virt: acrn: Prefer array_size and struct_size over open coded arithmetic
  afs: Prefer struct_size over open coded arithmetic

drivers/virt/acrn/acrn_drv.h

@@ -48,6 +48,7 @@ struct vm_memory_region_op {
  * @reserved:		Reserved.
  * @regions_num:	The number of vm_memory_region_op.
  * @regions_gpa:	Physical address of a vm_memory_region_op array.
+ * @regions_op:		Flexible array of vm_memory_region_op.
  *
  * HC_VM_SET_MEMORY_REGIONS uses this structure to manage EPT mappings of
  * multiple memory regions of a User VM. A &struct vm_memory_region_batch
@@ -55,10 +56,11 @@ struct vm_memory_region_op {
  * ACRN Hypervisor.
  */
 struct vm_memory_region_batch {
-	u16	vmid;
-	u16	reserved[3];
-	u32	regions_num;
-	u64	regions_gpa;
+	u16			   vmid;
+	u16			   reserved[3];
+	u32			   regions_num;
+	u64			   regions_gpa;
+	struct vm_memory_region_op regions_op[];
 };
 
 /**

drivers/virt/acrn/mm.c

@@ -192,7 +192,7 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
 
 	/* Get the page number of the map region */
 	nr_pages = memmap->len >> PAGE_SHIFT;
-	pages = vzalloc(nr_pages * sizeof(struct page *));
+	pages = vzalloc(array_size(nr_pages, sizeof(*pages)));
 	if (!pages)
 		return -ENOMEM;
 
@@ -244,16 +244,15 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
 	}
 
 	/* Prepare the vm_memory_region_batch */
-	regions_info = kzalloc(sizeof(*regions_info) +
-			       sizeof(*vm_region) * nr_regions,
-			       GFP_KERNEL);
+	regions_info = kzalloc(struct_size(regions_info, regions_op,
+					   nr_regions), GFP_KERNEL);
 	if (!regions_info) {
 		ret = -ENOMEM;
 		goto unmap_kernel_map;
 	}
 
 	/* Fill each vm_memory_region_op */
-	vm_region = (struct vm_memory_region_op *)(regions_info + 1);
+	vm_region = regions_info->regions_op;
 	regions_info->vmid = vm->vmid;
 	regions_info->regions_num = nr_regions;
 	regions_info->regions_gpa = virt_to_phys(vm_region);

fs/afs/security.c

@@ -219,8 +219,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
 	 * yet.
 	 */
 	size++;
-	new = kzalloc(sizeof(struct afs_permits) +
-		      sizeof(struct afs_permit) * size, GFP_NOFS);
+	new = kzalloc(struct_size(new, permits, size), GFP_NOFS);
 	if (!new)
 		goto out_put;