From 27977b69e493c9b259eb0490534e0f74bc325ba8 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Fri, 17 Jul 2015 11:33:16 -0400 Subject: [PATCH] ext4 crypto: check for too-short encrypted file names An encrypted file name should never be shorter than an 16 bytes, the AES block size. The 3.10 crypto layer will oops and crash the kernel if ciphertext shorter than the block size is passed to it. Fortunately, in modern kernels the crypto layer will not crash the kernel in this scenario, but nevertheless, it represents a corrupted directory, and we should detect it and mark the file system as corrupted so that e2fsck can fix this. Signed-off-by: Theodore Ts'o --- fs/ext4/crypto_fname.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/ext4/crypto_fname.c b/fs/ext4/crypto_fname.c index 7dc4eb55913c..86ee996a2bd4 100644 --- a/fs/ext4/crypto_fname.c +++ b/fs/ext4/crypto_fname.c @@ -329,6 +329,10 @@ int _ext4_fname_disk_to_usr(struct inode *inode, return oname->len; } } + if (iname->len < EXT4_CRYPTO_BLOCK_SIZE) { + EXT4_ERROR_INODE(inode, "encrypted inode too small"); + return -EUCLEAN; + } if (EXT4_I(inode)->i_crypt_info) return ext4_fname_decrypt(inode, iname, oname);