Merge tag 'ext4_for_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
"A security fix (so a maliciously corrupted file system image won't
panic the kernel) and some fixes for CONFIG_VMAP_STACK"

* tag 'ext4_for_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: sanity check the block and cluster size at mount time
fscrypto: don't use on-stack buffer for key derivation
fscrypto: don't use on-stack buffer for filename encryption

fs/crypto/fname.c

···
 static int fname_encrypt(struct inode *inode,
 			const struct qstr *iname, struct fscrypt_str *oname)
 {
-	u32 ciphertext_len;
 	struct skcipher_request *req = NULL;
 	DECLARE_FS_COMPLETION_RESULT(ecr);
 	struct fscrypt_info *ci = inode->i_crypt_info;
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
 	int res = 0;
 	char iv[FS_CRYPTO_BLOCK_SIZE];
-	struct scatterlist src_sg, dst_sg;
+	struct scatterlist sg;
 	int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
-	char *workbuf, buf[32], *alloc_buf = NULL;
-	unsigned lim;
+	unsigned int lim;
+	unsigned int cryptlen;
 
 	lim = inode->i_sb->s_cop->max_namelen(inode);
 	if (iname->len <= 0 || iname->len > lim)
 		return -EIO;
 
-	ciphertext_len = max(iname->len, (u32)FS_CRYPTO_BLOCK_SIZE);
-	ciphertext_len = round_up(ciphertext_len, padding);
-	ciphertext_len = min(ciphertext_len, lim);
+	/*
+	 * Copy the filename to the output buffer for encrypting in-place and
+	 * pad it with the needed number of NUL bytes.
+	 */
+	cryptlen = max_t(unsigned int, iname->len, FS_CRYPTO_BLOCK_SIZE);
+	cryptlen = round_up(cryptlen, padding);
+	cryptlen = min(cryptlen, lim);
+	memcpy(oname->name, iname->name, iname->len);
+	memset(oname->name + iname->len, 0, cryptlen - iname->len);
 
-	if (ciphertext_len <= sizeof(buf)) {
-		workbuf = buf;
-	} else {
-		alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
-		if (!alloc_buf)
-			return -ENOMEM;
-		workbuf = alloc_buf;
-	}
+	/* Initialize the IV */
+	memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
 
-	/* Allocate request */
+	/* Set up the encryption request */
 	req = skcipher_request_alloc(tfm, GFP_NOFS);
 	if (!req) {
 		printk_ratelimited(KERN_ERR
-			"%s: crypto_request_alloc() failed\n", __func__);
-		kfree(alloc_buf);
+			"%s: skcipher_request_alloc() failed\n", __func__);
 		return -ENOMEM;
 	}
 	skcipher_request_set_callback(req,
 			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 			fname_crypt_complete, &ecr);
+	sg_init_one(&sg, oname->name, cryptlen);
+	skcipher_request_set_crypt(req, &sg, &sg, cryptlen, iv);
 
-	/* Copy the input */
-	memcpy(workbuf, iname->name, iname->len);
-	if (iname->len < ciphertext_len)
-		memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
-
-	/* Initialize IV */
-	memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
-
-	/* Create encryption request */
-	sg_init_one(&src_sg, workbuf, ciphertext_len);
-	sg_init_one(&dst_sg, oname->name, ciphertext_len);
-	skcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
+	/* Do the encryption */
 	res = crypto_skcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
+		/* Request is being completed asynchronously; wait for it */
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
-	kfree(alloc_buf);
 	skcipher_request_free(req);
 	if (res < 0) {
 		printk_ratelimited(KERN_ERR
···
 		return res;
 	}
 
-	oname->len = ciphertext_len;
+	oname->len = cryptlen;
 	return 0;
 }
 

fs/crypto/keyinfo.c

···
 	struct crypto_skcipher *ctfm;
 	const char *cipher_str;
 	int keysize;
-	u8 raw_key[FS_MAX_KEY_SIZE];
+	u8 *raw_key = NULL;
 	int res;
 
 	res = fscrypt_initialize();
···
 	if (res)
 		goto out;
 
+	/*
+	 * This cannot be a stack buffer because it is passed to the scatterlist
+	 * crypto API as part of key derivation.
+	 */
+	res = -ENOMEM;
+	raw_key = kmalloc(FS_MAX_KEY_SIZE, GFP_NOFS);
+	if (!raw_key)
+		goto out;
+
 	if (fscrypt_dummy_context_enabled(inode)) {
 		memset(raw_key, 0x42, FS_AES_256_XTS_KEY_SIZE);
 		goto got_key;
···
 	if (res)
 		goto out;
 
-	memzero_explicit(raw_key, sizeof(raw_key));
+	kzfree(raw_key);
+	raw_key = NULL;
 	if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) != NULL) {
 		put_crypt_info(crypt_info);
 		goto retry;
···
 	if (res == -ENOKEY)
 		res = 0;
 	put_crypt_info(crypt_info);
-	memzero_explicit(raw_key, sizeof(raw_key));
+	kzfree(raw_key);
 	return res;
 }
 

fs/ext4/ext4.h

···
 #define	EXT4_MAX_BLOCK_SIZE		65536
 #define EXT4_MIN_BLOCK_LOG_SIZE		10
 #define EXT4_MAX_BLOCK_LOG_SIZE		16
+#define EXT4_MAX_CLUSTER_LOG_SIZE	30
 #ifdef __KERNEL__
 # define EXT4_BLOCK_SIZE(s)		((s)->s_blocksize)
 #else

fs/ext4/super.c

···
 	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
 	    blocksize > EXT4_MAX_BLOCK_SIZE) {
 		ext4_msg(sb, KERN_ERR,
-		       "Unsupported filesystem blocksize %d", blocksize);
+		       "Unsupported filesystem blocksize %d (%d log_block_size)",
+			 blocksize, le32_to_cpu(es->s_log_block_size));
+		goto failed_mount;
+	}
+	if (le32_to_cpu(es->s_log_block_size) >
+	    (EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Invalid log block size: %u",
+			 le32_to_cpu(es->s_log_block_size));
 		goto failed_mount;
 	}
 
···
 			ext4_msg(sb, KERN_ERR,
 				 "cluster size (%d) smaller than "
 				 "block size (%d)", clustersize, blocksize);
+			goto failed_mount;
+		}
+		if (le32_to_cpu(es->s_log_cluster_size) >
+		    (EXT4_MAX_CLUSTER_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Invalid log cluster size: %u",
+				 le32_to_cpu(es->s_log_cluster_size));
 			goto failed_mount;
 		}
 		sbi->s_cluster_bits = le32_to_cpu(es->s_log_cluster_size) -