[linux-cifs-client] [PATCH] cifs: fix error handling in mount-time DFS referral chasing code

[Igor Mammedov]

Looks good to me:

Acked-by: Igor Mammedov <niallain at gmail.com>

Jeff Layton wrote:
> If the referral is malformed or the hostname can't be resolved, then
> the current code generates an oops. Fix it to handle these errors
> gracefully.
> 
> Reported-by: Sandro Mathys <sm at sandro-mathys.ch>
> Signed-off-by: Jeff Layton <jlayton at redhat.com>
> ---
>  fs/cifs/cifs_dfs_ref.c |   12 +++++++++---
>  fs/cifs/connect.c      |   13 ++++++++++---
>  2 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
> index 3bb11be..606912d 100644
> --- a/fs/cifs/cifs_dfs_ref.c
> +++ b/fs/cifs/cifs_dfs_ref.c
> @@ -55,7 +55,7 @@ void cifs_dfs_release_automount_timer(void)
>   * i.e. strips from UNC trailing path that is not part of share
>   * name and fixup missing '\' in the begining of DFS node refferal
>   * if neccessary.
> - * Returns pointer to share name on success or NULL on error.
> + * Returns pointer to share name on success or ERR_PTR on error.
>   * Caller is responsible for freeing returned string.
>   */
>  static char *cifs_get_share_name(const char *node_name)
> @@ -68,7 +68,7 @@ static char *cifs_get_share_name(const char *node_name)
>  	UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
>  			 GFP_KERNEL);
>  	if (!UNC)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>  
>  	/* get share name and server name */
>  	if (node_name[1] != '\\') {
> @@ -87,7 +87,7 @@ static char *cifs_get_share_name(const char *node_name)
>  		cERROR(1, ("%s: no server name end in node name: %s",
>  			__func__, node_name));
>  		kfree(UNC);
> -		return NULL;
> +		return ERR_PTR(-EINVAL);
>  	}
>  
>  	/* find sharename end */
> @@ -133,6 +133,12 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
>  		return ERR_PTR(-EINVAL);
>  
>  	*devname = cifs_get_share_name(ref->node_name);
> +	if (IS_ERR(*devname)) {
> +		rc = PTR_ERR(*devname);
> +		*devname = NULL;
> +		goto compose_mount_options_err;
> +	}
> +
>  	rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
>  	if (rc != 0) {
>  		cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d",
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index fc44d31..f248688 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -2544,11 +2544,20 @@ remote_path_check:
>  
>  			if (mount_data != mount_data_global)
>  				kfree(mount_data);
> +
>  			mount_data = cifs_compose_mount_options(
>  					cifs_sb->mountdata, full_path + 1,
>  					referrals, &fake_devname);
> -			kfree(fake_devname);
> +
>  			free_dfs_info_array(referrals, num_referrals);
> +			kfree(fake_devname);
> +			kfree(full_path);
> +
> +			if (IS_ERR(mount_data)) {
> +				rc = PTR_ERR(mount_data);
> +				mount_data = NULL;
> +				goto mount_fail_check;
> +			}
>  
>  			if (tcon)
>  				cifs_put_tcon(tcon);
> @@ -2556,8 +2565,6 @@ remote_path_check:
>  				cifs_put_smb_ses(pSesInfo);
>  
>  			cleanup_volume_info(&volume_info);
> -			FreeXid(xid);
> -			kfree(full_path);
>  			referral_walks_count++;
>  			goto try_mount_again;
>  		}

-- 

Best regards,

-------------------------
Igor Mammedov,
niallain "at" gmail.com