ANDROID: Incremental fs: Pad hash blocks

Test: incfs_test passes
Bug: 133435829
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Change-Id: I4e6fbd0938f00e7e6883ce1a26cbfd38fdcaa9a5

fs/incfs/integrity.c

@@ -198,6 +198,20 @@ int incfs_calc_digest(struct incfs_hash_alg *alg, struct mem_range data,
 		return -EINVAL;
 
 	desc->tfm = alg->shash;
+
+	if (data.len < INCFS_DATA_FILE_BLOCK_SIZE) {
+		int err;
+		void *buf = kzalloc(INCFS_DATA_FILE_BLOCK_SIZE, GFP_NOFS);
+
+		if (!buf)
+			return -ENOMEM;
+
+		memcpy(buf, data.data, data.len);
+		err = crypto_shash_digest(desc, buf, INCFS_DATA_FILE_BLOCK_SIZE,
+					  digest.data);
+		kfree(buf);
+		return err;
+	}
 	return crypto_shash_digest(desc, data.data, data.len, digest.data);
 }
 

tools/testing/selftests/filesystems/incfs/incfs_test.c

@@ -750,8 +750,9 @@ static int build_mtree(struct test_file *file)
 	if (block_count == 1) {
 		int seed = get_file_block_seed(file->index, 0);
 
+		memset(data, 0, INCFS_DATA_FILE_BLOCK_SIZE);
 		rnd_buf((uint8_t *)data, file->size, seed);
-		sha256(data, file->size, file->root_hash);
+		sha256(data, INCFS_DATA_FILE_BLOCK_SIZE, file->root_hash);
 		return 0;
 	}
 
@@ -766,11 +767,13 @@ static int build_mtree(struct test_file *file)
 		int seed = get_file_block_seed(file->index, i);
 		char *hash_ptr = file->mtree[block_index].data + block_off;
 
-		if (file->size - offset < block_size)
+		if (file->size - offset < block_size) {
 			block_size = file->size - offset;
+			memset(data, 0, INCFS_DATA_FILE_BLOCK_SIZE);
+		}
 
 		rnd_buf((uint8_t *)data, block_size, seed);
-		sha256(data, block_size, hash_ptr);
+		sha256(data, INCFS_DATA_FILE_BLOCK_SIZE, hash_ptr);
 	}
 
 	/* Build higher levels of hash tree. */