PM: hibernate: Don't ignore return from set_memory_ro()

set_memory_ro() and set_memory_rw() can fail, leaving memory
unprotected.

Take the returned value into account and abort in case of
failure.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: chleroy

kernel/power/power.h

@@ -153,7 +153,7 @@ extern unsigned int snapshot_additional_pages(struct zone *zone);
 extern unsigned long snapshot_get_image_size(void);
 extern int snapshot_read_next(struct snapshot_handle *handle);
 extern int snapshot_write_next(struct snapshot_handle *handle);
-extern void snapshot_write_finalize(struct snapshot_handle *handle);
+int snapshot_write_finalize(struct snapshot_handle *handle);
 extern int snapshot_image_loaded(struct snapshot_handle *handle);
 
 extern bool hibernate_acquire(void);

kernel/power/snapshot.c

@@ -58,22 +58,24 @@ static inline void hibernate_restore_protection_end(void)
 	hibernate_restore_protection_active = false;
 }
 
-static inline void hibernate_restore_protect_page(void *page_address)
+static inline int __must_check hibernate_restore_protect_page(void *page_address)
 {
 	if (hibernate_restore_protection_active)
-		set_memory_ro((unsigned long)page_address, 1);
+		return set_memory_ro((unsigned long)page_address, 1);
+	return 0;
 }
 
-static inline void hibernate_restore_unprotect_page(void *page_address)
+static inline int hibernate_restore_unprotect_page(void *page_address)
 {
 	if (hibernate_restore_protection_active)
-		set_memory_rw((unsigned long)page_address, 1);
+		return set_memory_rw((unsigned long)page_address, 1);
+	return 0;
 }
 #else
 static inline void hibernate_restore_protection_begin(void) {}
 static inline void hibernate_restore_protection_end(void) {}
-static inline void hibernate_restore_protect_page(void *page_address) {}
-static inline void hibernate_restore_unprotect_page(void *page_address) {}
+static inline int __must_check hibernate_restore_protect_page(void *page_address) {return 0; }
+static inline int hibernate_restore_unprotect_page(void *page_address) {return 0; }
 #endif /* CONFIG_STRICT_KERNEL_RWX  && CONFIG_ARCH_HAS_SET_MEMORY */
 
 
@@ -2832,7 +2834,9 @@ int snapshot_write_next(struct snapshot_handle *handle)
 		}
 	} else {
 		copy_last_highmem_page();
-		hibernate_restore_protect_page(handle->buffer);
+		error = hibernate_restore_protect_page(handle->buffer);
+		if (error)
+			return error;
 		handle->buffer = get_buffer(&orig_bm, &ca);
 		if (IS_ERR(handle->buffer))
 			return PTR_ERR(handle->buffer);
@@ -2858,15 +2862,18 @@ int snapshot_write_next(struct snapshot_handle *handle)
  * stored in highmem.  Additionally, it recycles bitmap memory that's not
  * necessary any more.
  */
-void snapshot_write_finalize(struct snapshot_handle *handle)
+int snapshot_write_finalize(struct snapshot_handle *handle)
 {
+	int error;
+
 	copy_last_highmem_page();
-	hibernate_restore_protect_page(handle->buffer);
+	error = hibernate_restore_protect_page(handle->buffer);
 	/* Do that only if we have loaded the image entirely */
 	if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages + nr_zero_pages) {
 		memory_bm_recycle(&orig_bm);
 		free_highmem_data();
 	}
+	return error;
 }
 
 int snapshot_image_loaded(struct snapshot_handle *handle)

kernel/power/swap.c

@@ -1134,8 +1134,8 @@ static int load_image(struct swap_map_handle *handle,
 		ret = err2;
 	if (!ret) {
 		pr_info("Image loading done\n");
-		snapshot_write_finalize(snapshot);
-		if (!snapshot_image_loaded(snapshot))
+		ret = snapshot_write_finalize(snapshot);
+		if (!ret && !snapshot_image_loaded(snapshot))
 			ret = -ENODATA;
 	}
 	swsusp_show_speed(start, stop, nr_to_read, "Read");
@@ -1486,8 +1486,8 @@ static int load_compressed_image(struct swap_map_handle *handle,
 	stop = ktime_get();
 	if (!ret) {
 		pr_info("Image loading done\n");
-		snapshot_write_finalize(snapshot);
-		if (!snapshot_image_loaded(snapshot))
+		ret = snapshot_write_finalize(snapshot);
+		if (!ret && !snapshot_image_loaded(snapshot))
 			ret = -ENODATA;
 		if (!ret) {
 			if (swsusp_header->flags & SF_CRC32_MODE) {

kernel/power/user.c

@@ -317,7 +317,9 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		break;
 
 	case SNAPSHOT_ATOMIC_RESTORE:
-		snapshot_write_finalize(&data->handle);
+		error = snapshot_write_finalize(&data->handle);
+		if (error)
+			break;
 		if (data->mode != O_WRONLY || !data->frozen ||
 		    !snapshot_image_loaded(&data->handle)) {
 			error = -EPERM;