linux-kernel - [PATCH AUTOSEL 4.19 025/158] fscrypt: clean up some BUG

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Date:   Mon, 15 Jul 2019 10:15:56 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Eric Biggers <ebiggers@...gle.com>,
        Chandan Rajendra <chandan@...ux.ibm.com>,
        Sasha Levin <sashal@...nel.org>, linux-fscrypt@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 025/158] fscrypt: clean up some BUG_ON()s in block encryption/decryption

From: Eric Biggers <ebiggers@...gle.com>

[ Upstream commit eeacfdc68a104967162dfcba60f53f6f5b62a334 ]

Replace some BUG_ON()s with WARN_ON_ONCE() and returning an error code,
and move the check for len divisible by FS_CRYPTO_BLOCK_SIZE into
fscrypt_crypt_block() so that it's done for both encryption and
decryption, not just encryption.

Reviewed-by: Chandan Rajendra <chandan@...ux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/crypto/crypto.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 0f46cf550907..c83ddff3ff4a 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -149,7 +149,10 @@ int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
 	int res = 0;
 
-	BUG_ON(len == 0);
+	if (WARN_ON_ONCE(len <= 0))
+		return -EINVAL;
+	if (WARN_ON_ONCE(len % FS_CRYPTO_BLOCK_SIZE != 0))
+		return -EINVAL;
 
 	BUILD_BUG_ON(sizeof(iv) != FS_IV_SIZE);
 	BUILD_BUG_ON(AES_BLOCK_SIZE != FS_IV_SIZE);
@@ -241,8 +244,6 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 	struct page *ciphertext_page = page;
 	int err;
 
-	BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
-
 	if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
 		/* with inplace-encryption we just encrypt the page */
 		err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
@@ -254,7 +255,8 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 		return ciphertext_page;
 	}
 
-	BUG_ON(!PageLocked(page));
+	if (WARN_ON_ONCE(!PageLocked(page)))
+		return ERR_PTR(-EINVAL);
 
 	ctx = fscrypt_get_ctx(inode, gfp_flags);
 	if (IS_ERR(ctx))
@@ -302,8 +304,9 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
 int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
 			unsigned int len, unsigned int offs, u64 lblk_num)
 {
-	if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
-		BUG_ON(!PageLocked(page));
+	if (WARN_ON_ONCE(!PageLocked(page) &&
+			 !(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES)))
+		return -EINVAL;
 
 	return fscrypt_do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page,
 				      len, offs, GFP_NOFS);
-- 
2.20.1