smb3: add additional null check in SMB311_posix_mkdir

Although unlikely for it to be possible for rsp to be null here,
the check is safer to add, and quiets a Coverity warning.

Addresses-Coverity: 1437501 ("Explicit Null dereference")
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 243de87..5e032b2 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2668,7 +2668,18 @@ int smb311_posix_mkdir(const unsigned int xid, struct inode *inode,
                goto err_free_rsp_buf;
        }
 
+       /*
+        * Although unlikely to be possible for rsp to be null and rc not set,
+        * adding check below is slightly safer long term (and quiets Coverity
+        * warning)
+        */
        rsp = (struct smb2_create_rsp *)rsp_iov.iov_base;
+       if (rsp == NULL) {
+               rc = -EIO;
+               kfree(pc_buf);
+               goto err_free_req;
+       }
+
        trace_smb3_posix_mkdir_done(xid, le64_to_cpu(rsp->PersistentFileId),
                                    tcon->tid,
                                    ses->Suid, CREATE_NOT_FILE,