[PATCH] [jaunty] [Upstream]: eCryptfs: Handle unrecognized tag 3 cipher codes

[Stefan Bader]

Surbhi Palande wrote:
> SRU  Justification: 
> Impact:  Bug in the Ecryptfs disallowed saving the file under the ecryptfs
> directory ~/Private using Emacs.
> 
> Fix: The cherry picked patch with the upstream commit id
> "b0105eaefa7cce8f4a941d0fc6354b250d30e745" fixed this bug. Previous to this
> fix a cipher code was not recognized and as a result memory was not allocated
> to some pointer. However this pointer was freed even when the allocation was
> not done. This fix, prevents the freeing of memory when the cipher is not
> recognised and memory is not allocated.
> 
> Testcase: The reporter of the bug, has verified that this patch has fixed this
> bug for him.
> 
> ===
> 
> From d2504c185b312650445d95d2cfeac80309af237a Mon Sep 17 00:00:00 2001
> From: Tyler Hicks <tyhicks at linux.vnet.ibm.com>
> Date: Tue, 11 Aug 2009 00:36:32 -0500
> Subject: [PATCH] [jaunty] [Upstream]: eCryptfs: Handle unrecognized tag 3 cipher codes
> 
> BugLink: https://bugs.launchpad.net/bugs/415252
> 
> Returns an error when an unrecognized cipher code is present in a tag 3
> packet or an ecryptfs_crypt_stat cannot be initialized.  Also sets an
> crypt_stat->tfm error pointer to NULL to ensure that it will not be
> incorrectly freed in ecryptfs_destroy_crypt_stat().
> 
> Acked-by: Serge Hallyn <serue at us.ibm.com>
> Cc: ecryptfs-devel at lists.launchpad.net
> Cc: stable <stable at kernel.org>
> Signed-off-by: Tyler Hicks <tyhicks at linux.vnet.ibm.com>
> (cherry picked from commit b0105eaefa7cce8f4a941d0fc6354b250d30e745)
> Signed-off-by: Surbhi Palande <surbhi.palande at canonical.com>

Acked-by: Stefan Bader <stefan.bader at canonical.com>

> ---
>  fs/ecryptfs/crypto.c   |    1 +
>  fs/ecryptfs/keystore.c |   10 +++++++---
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
> index 8b65f28..bbf080b 100644
> --- a/fs/ecryptfs/crypto.c
> +++ b/fs/ecryptfs/crypto.c
> @@ -814,6 +814,7 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
>  	kfree(full_alg_name);
>  	if (IS_ERR(crypt_stat->tfm)) {
>  		rc = PTR_ERR(crypt_stat->tfm);
> +		crypt_stat->tfm = NULL;
>  		ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
>  				"Error initializing cipher [%s]\n",
>  				crypt_stat->cipher);
> diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
> index 37bcb43..b41af15 100644
> --- a/fs/ecryptfs/keystore.c
> +++ b/fs/ecryptfs/keystore.c
> @@ -1317,8 +1317,10 @@ parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
>  		rc = -EINVAL;
>  		goto out_free;
>  	}
> -	ecryptfs_cipher_code_to_string(crypt_stat->cipher,
> -				       (u16)data[(*packet_size)]);
> +	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
> +					    (u16)data[(*packet_size)]);
> +	if (rc)
> +		goto out_free;
>  	/* A little extra work to differentiate among the AES key
>  	 * sizes; see RFC2440 */
>  	switch(data[(*packet_size)++]) {
> @@ -1329,7 +1331,9 @@ parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
>  		crypt_stat->key_size =
>  			(*new_auth_tok)->session_key.encrypted_key_size;
>  	}
> -	ecryptfs_init_crypt_ctx(crypt_stat);
> +	rc = ecryptfs_init_crypt_ctx(crypt_stat);
> +	if (rc)
> +		goto out_free;
>  	if (unlikely(data[(*packet_size)++] != 0x03)) {
>  		printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
>  		rc = -ENOSYS;