1 files changed, 35 insertions, 12 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 47d8ff623683..8d6c17ab593d 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -337,8 +337,13 @@ cifs_echo_request(struct work_struct *work)
         struct TCP_Server_Info *server = container_of(work,
                                         struct TCP_Server_Info, echo.work);
 
-        /* no need to ping if we got a response recently */
-        if (time_before(jiffies, server->lstrp + SMB_ECHO_INTERVAL - HZ))
+        /*
+         * We cannot send an echo until the NEGOTIATE_PROTOCOL request is
+         * done, which is indicated by maxBuf != 0. Also, no need to ping if
+         * we got a response recently
+         */
+        if (server->maxBuf == 0 ||
+            time_before(jiffies, server->lstrp + SMB_ECHO_INTERVAL - HZ))
                 goto requeue_echo;
 
         rc = CIFSSMBEcho(server);
@@ -578,14 +583,23 @@ incomplete_rcv:
                 else if (reconnect == 1)
                         continue;
 
-                length += 4; /* account for rfc1002 hdr */
+                total_read += 4; /* account for rfc1002 hdr */
 
+                dump_smb(smb_buffer, total_read);
 
-                dump_smb(smb_buffer, length);
-                if (checkSMB(smb_buffer, smb_buffer->Mid, total_read+4)) {
-                        cifs_dump_mem("Bad SMB: ", smb_buffer, 48);
-                        continue;
-                }
+                /*
+                 * 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,
+                                        min_t(unsigned int, total_read, 48));
 
                 mid_entry = NULL;
                 server->lstrp = jiffies;
@@ -597,7 +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) {
@@ -632,12 +647,17 @@ incomplete_rcv:
                                 mid_entry->resp_buf = smb_buffer;
                                 mid_entry->largeBuf = isLargeBuf;
 multi_t2_fnd:
-                                mid_entry->midState = MID_RESPONSE_RECEIVED;
-                                list_del_init(&mid_entry->qhead);
-                                mid_entry->callback(mid_entry);
+                                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
+                                list_del_init(&mid_entry->qhead);
+                                mid_entry->callback(mid_entry);
                                 break;
                         }
                         mid_entry = NULL;
@@ -653,6 +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! "