cifs: clean up unaligned accesses in validate_t2

...and clean up function to reduce indentation.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 23 insertions, 21 deletions

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 39cec0d9cd1b..675041a6949c 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -331,31 +331,33 @@ smb_init_no_reconnect(int smb_command, int wct, struct cifsTconInfo *tcon,
 
 static int validate_t2(struct smb_t2_rsp *pSMB)
 {
-        int rc = -EINVAL;
-        int total_size;
+        unsigned int total_size;
+
+        /* check for plausible wct */
+        if (pSMB->hdr.WordCount < 10)
+                goto vt2_err;
 
-        /* check for plausible wct, bcc and t2 data and parm sizes */
         /* check for parm and data offset going beyond end of smb */
-        if (pSMB->hdr.WordCount >= 10) {
-                if ((le16_to_cpu(pSMB->t2_rsp.ParameterOffset) <= 1024) &&
-                   (le16_to_cpu(pSMB->t2_rsp.DataOffset) <= 1024)) {
-                        /* check that bcc is at least as big as parms + data */
-                        /* check that bcc is less than negotiated smb buffer */
-                        total_size = le16_to_cpu(pSMB->t2_rsp.ParameterCount);
-                        if (total_size < 512) {
-                                total_size +=
-                                        le16_to_cpu(pSMB->t2_rsp.DataCount);
-                                if (total_size <= get_bcc(&pSMB->hdr) &&
-                                    total_size <
-                                        CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) {
-                                        return 0;
-                                }
-                        }
-                }
-        }
+        if (get_unaligned_le16(&pSMB->t2_rsp.ParameterOffset) > 1024 ||
+            get_unaligned_le16(&pSMB->t2_rsp.DataOffset) > 1024)
+                goto vt2_err;
+
+        /* check that bcc is at least as big as parms + data */
+        /* check that bcc is less than negotiated smb buffer */
+        total_size = get_unaligned_le16(&pSMB->t2_rsp.ParameterCount);
+        if (total_size >= 512)
+                goto vt2_err;
+
+        total_size += get_unaligned_le16(&pSMB->t2_rsp.DataCount);
+        if (total_size > get_bcc(&pSMB->hdr) ||
+            total_size >= CIFSMaxBufSize + MAX_CIFS_HDR_SIZE)
+                goto vt2_err;
+
+        return 0;
+vt2_err:
         cifs_dump_mem("Invalid transact2 SMB: ", (char *)pSMB,
                 sizeof(struct smb_t2_rsp) + 16);
-        return rc;
+        return -EINVAL;
 }
 
 int