ext4 crypto: replace some BUG_ON()'s with error checks

commit 687c3c36 upstream.

Buggy (or hostile) userspace should not be able to cause the kernel to
crash.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ext4/crypto.c

@@ -296,7 +296,6 @@ static int ext4_page_crypto(struct ext4_crypto_ctx *ctx,
 	else
 		res = crypto_ablkcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}

fs/ext4/crypto_fname.c

@@ -121,7 +121,6 @@ static int ext4_fname_encrypt(struct inode *inode,
 	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
 	res = crypto_ablkcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
@@ -183,7 +182,6 @@ static int ext4_fname_decrypt(struct inode *inode,
 	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
 	res = crypto_ablkcipher_decrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}

fs/ext4/crypto_key.c

@@ -71,7 +71,6 @@ static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],
 				     EXT4_AES_256_XTS_KEY_SIZE, NULL);
 	res = crypto_ablkcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
@@ -208,7 +207,12 @@ int _ext4_get_encryption_info(struct inode *inode)
 		goto out;
 	}
 	crypt_info->ci_keyring_key = keyring_key;
-	BUG_ON(keyring_key->type != &key_type_logon);
+	if (keyring_key->type != &key_type_logon) {
+		printk_once(KERN_WARNING
+			    "ext4: key type must be logon\n");
+		res = -ENOKEY;
+		goto out;
+	}
 	ukp = ((struct user_key_payload *)keyring_key->payload.data);
 	if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
 		res = -EINVAL;
@@ -217,7 +221,13 @@ int _ext4_get_encryption_info(struct inode *inode)
 	master_key = (struct ext4_encryption_key *)ukp->data;
 	BUILD_BUG_ON(EXT4_AES_128_ECB_KEY_SIZE !=
 		     EXT4_KEY_DERIVATION_NONCE_SIZE);
-	BUG_ON(master_key->size != EXT4_AES_256_XTS_KEY_SIZE);
+	if (master_key->size != EXT4_AES_256_XTS_KEY_SIZE) {
+		printk_once(KERN_WARNING
+			    "ext4: key size incorrect: %d\n",
+			    master_key->size);
+		res = -ENOKEY;
+		goto out;
+	}
 	res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
 				  raw_key);
 got_key:

fs/ext4/crypto_policy.c

@@ -137,7 +137,8 @@ int ext4_is_child_context_consistent_with_parent(struct inode *parent,
 
 	if ((parent == NULL) || (child == NULL)) {
 		pr_err("parent %p child %p\n", parent, child);
-		BUG_ON(1);
+		WARN_ON(1);	/* Should never happen */
+		return 0;
 	}
 	/* no restrictions if the parent directory is not encrypted */
 	if (!ext4_encrypted_inode(parent))