3 files changed, 28 insertions, 7 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 1ab33eb71d95..17afb0fbcaed 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -654,7 +654,7 @@ static inline void free_dfs_info_array(struct dfs_info3_param *param,
 #define   MID_REQUEST_SUBMITTED 2
 #define   MID_RESPONSE_RECEIVED 4
 #define   MID_RETRY_NEEDED      8 /* session closed while this request out */
-#define   MID_NO_RESP_NEEDED 0x10
+#define   MID_RESPONSE_MALFORMED 0x10
 
 /* Types of response buffer returned from SendReceive2 */
 #define   CIFS_NO_BUFFER        0    /* Response buffer not returned */
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 161f24ca4f6e..8d6c17ab593d 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -586,11 +586,20 @@ incomplete_rcv:
                 total_read += 4; /* account for rfc1002 hdr */
 
                 dump_smb(smb_buffer, total_read);
-                if (checkSMB(smb_buffer, smb_buffer->Mid, total_read)) {
+
+                /*
+                 * We know that we received enough to get to the MID as we
+                 * checked the pdu_length earlier. Now check to see
+                 * if the rest of the header is OK. We borrow the length
+                 * var for the rest of the loop to avoid a new stack var.
+                 *
+                 * 48 bytes is enough to display the header and a little bit
+                 * into the payload for debugging purposes.
+                 */
+                length = checkSMB(smb_buffer, smb_buffer->Mid, total_read);
+                if (length != 0)
                         cifs_dump_mem("Bad SMB: ", smb_buffer,
-                                        total_read < 48 ? total_read : 48);
-                        continue;
-                }
+                                        min_t(unsigned int, total_read, 48));
 
                 mid_entry = NULL;
                 server->lstrp = jiffies;
@@ -602,7 +611,8 @@ incomplete_rcv:
                         if ((mid_entry->mid == smb_buffer->Mid) &&
                             (mid_entry->midState == MID_REQUEST_SUBMITTED) &&
                             (mid_entry->command == smb_buffer->Command)) {
-                                if (check2ndT2(smb_buffer,server->maxBuf) > 0) {
+                                if (length == 0 &&
+                                   check2ndT2(smb_buffer, server->maxBuf) > 0) {
                                         /* We have a multipart transact2 resp */
                                         isMultiRsp = true;
                                         if (mid_entry->resp_buf) {
@@ -637,7 +647,12 @@ incomplete_rcv:
                                 mid_entry->resp_buf = smb_buffer;
                                 mid_entry->largeBuf = isLargeBuf;
 multi_t2_fnd:
-                                mid_entry->midState = MID_RESPONSE_RECEIVED;
+                                if (length == 0)
+                                        mid_entry->midState =
+                                                        MID_RESPONSE_RECEIVED;
+                                else
+                                        mid_entry->midState =
+                                                        MID_RESPONSE_MALFORMED;
 #ifdef CONFIG_CIFS_STATS2
                                 mid_entry->when_received = jiffies;
 #endif
@@ -658,6 +673,9 @@ multi_t2_fnd:
                                 else
                                         smallbuf = NULL;
                         }
+                } else if (length != 0) {
+                        /* response sanity checks failed */
+                        continue;
                 } else if (!is_valid_oplock_break(smb_buffer, server) &&
                            !isMultiRsp) {
                         cERROR(1, "No task to wake, unknown frame received! "
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index fbc5aace54b1..46d8756f2b24 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -457,6 +457,9 @@ sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
         case MID_RETRY_NEEDED:
                 rc = -EAGAIN;
                 break;
+        case MID_RESPONSE_MALFORMED:
+                rc = -EIO;
+                break;
         default:
                 cERROR(1, "%s: invalid mid state mid=%d state=%d", __func__,
                         mid->mid, mid->midState);