[PATCH v2] cifs: extend the buffer length enought for sprintf() using

[Steve French]

merged into cifs-2.6.git

On Fri, Jul 19, 2013 at 5:45 AM, Jeff Layton <jlayton at redhat.com> wrote:
> On Fri, 19 Jul 2013 09:01:36 +0800
> Chen Gang <gang.chen at asianux.com> wrote:
>
>> For cifs_set_cifscreds() in "fs/cifs/connect.c", 'desc' buffer length
>> is 'CIFSCREDS_DESC_SIZE' (56 is less than 256), and 'ses->domainName'
>> length may be "255 + '\0'".
>>
>> The related sprintf() may cause memory overflow, so need extend related
>> buffer enough to hold all things.
>>
>> It is also necessary to be sure of 'ses->domainName' must be less than
>> 256, and define the related macro instead of hard code number '256'.
>>
>> Signed-off-by: Chen Gang <gang.chen at asianux.com>
>> ---
>>  fs/cifs/cifsencrypt.c |    2 +-
>>  fs/cifs/cifsglob.h    |    1 +
>>  fs/cifs/connect.c     |    7 ++++---
>>  fs/cifs/sess.c        |    6 +++---
>>  4 files changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
>> index 45e57cc..bb84d7c 100644
>> --- a/fs/cifs/cifsencrypt.c
>> +++ b/fs/cifs/cifsencrypt.c
>> @@ -421,7 +421,7 @@ find_domain_name(struct cifs_ses *ses, const struct nls_table *nls_cp)
>>               if (blobptr + attrsize > blobend)
>>                       break;
>>               if (type == NTLMSSP_AV_NB_DOMAIN_NAME) {
>> -                     if (!attrsize)
>> +                     if (!attrsize || attrsize >= MAX_DOMAINNAME_SIZE)
>>                               break;
>>                       if (!ses->domainName) {
>>                               ses->domainName =
>> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
>> index 33f17ed..64bb4c5 100644
>> --- a/fs/cifs/cifsglob.h
>> +++ b/fs/cifs/cifsglob.h
>> @@ -44,6 +44,7 @@
>>  #define MAX_TREE_SIZE (2 + MAX_SERVER_SIZE + 1 + MAX_SHARE_SIZE + 1)
>>  #define MAX_SERVER_SIZE 15
>>  #define MAX_SHARE_SIZE 80
>> +#define MAX_DOMAINNAME_SIZE 256      /* maximum fully qualified domain name (FQDN) */
>>  #define MAX_USERNAME_SIZE 256        /* reasonable maximum for current servers */
>>  #define MAX_PASSWORD_SIZE 512        /* max for windows seems to be 256 wide chars */
>>
>> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
>> index fa68813..3f9dcf7 100644
>> --- a/fs/cifs/connect.c
>> +++ b/fs/cifs/connect.c
>> @@ -1675,7 +1675,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>>                       if (string == NULL)
>>                               goto out_nomem;
>>
>> -                     if (strnlen(string, 256) == 256) {
>> +                     if (strnlen(string, MAX_DOMAINNAME_SIZE)
>> +                                     == MAX_DOMAINNAME_SIZE) {
>>                               printk(KERN_WARNING "CIFS: domain name too"
>>                                                   " long\n");
>>                               goto cifs_parse_mount_err;
>> @@ -2276,8 +2277,8 @@ cifs_put_smb_ses(struct cifs_ses *ses)
>>
>>  #ifdef CONFIG_KEYS
>>
>> -/* strlen("cifs:a:") + INET6_ADDRSTRLEN + 1 */
>> -#define CIFSCREDS_DESC_SIZE (7 + INET6_ADDRSTRLEN + 1)
>> +/* strlen("cifs:a:") + MAX_DOMAINNAME_SIZE + 1 */
>> +#define CIFSCREDS_DESC_SIZE (7 + MAX_DOMAINNAME_SIZE + 1)
>>
>>  /* Populate username and pw fields from keyring if possible */
>>  static int
>> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
>> index 79358e3..57b1537 100644
>> --- a/fs/cifs/sess.c
>> +++ b/fs/cifs/sess.c
>> @@ -197,7 +197,7 @@ static void unicode_domain_string(char **pbcc_area, struct cifs_ses *ses,
>>               bytes_ret = 0;
>>       } else
>>               bytes_ret = cifs_strtoUTF16((__le16 *) bcc_ptr, ses->domainName,
>> -                                         256, nls_cp);
>> +                                         MAX_DOMAINNAME_SIZE, nls_cp);
>>       bcc_ptr += 2 * bytes_ret;
>>       bcc_ptr += 2;  /* account for null terminator */
>>
>> @@ -255,8 +255,8 @@ static void ascii_ssetup_strings(char **pbcc_area, struct cifs_ses *ses,
>>
>>       /* copy domain */
>>       if (ses->domainName != NULL) {
>> -             strncpy(bcc_ptr, ses->domainName, 256);
>> -             bcc_ptr += strnlen(ses->domainName, 256);
>> +             strncpy(bcc_ptr, ses->domainName, MAX_DOMAINNAME_SIZE);
>> +             bcc_ptr += strnlen(ses->domainName, MAX_DOMAINNAME_SIZE);
>>       } /* else we will send a null domain name
>>            so the server will default to its own domain */
>>       *bcc_ptr = 0;
>
> Looks good...
>
> Reviewed-by: Jeff Layton <jlayton at redhat.com>



-- 
Thanks,

Steve