smb: client: fix potential OOB in cifs_dump_detail()

Validate SMB message with ->check_message() before calling
->calc_smb_size().
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/cifs_debug.c

@@ -40,11 +40,13 @@ void cifs_dump_detail(void *buf, struct TCP_Server_Info *server)
 #ifdef CONFIG_CIFS_DEBUG2
 	struct smb_hdr *smb = buf;
 
-	cifs_dbg(VFS, "Cmd: %d Err: 0x%x Flags: 0x%x Flgs2: 0x%x Mid: %d Pid: %d\n",
-		 smb->Command, smb->Status.CifsError,
-		 smb->Flags, smb->Flags2, smb->Mid, smb->Pid);
-	cifs_dbg(VFS, "smb buf %p len %u\n", smb,
-		 server->ops->calc_smb_size(smb));
+	cifs_dbg(VFS, "Cmd: %d Err: 0x%x Flags: 0x%x Flgs2: 0x%x Mid: %d Pid: %d Wct: %d\n",
+		 smb->Command, smb->Status.CifsError, smb->Flags,
+		 smb->Flags2, smb->Mid, smb->Pid, smb->WordCount);
+	if (!server->ops->check_message(buf, server->total_read, server)) {
+		cifs_dbg(VFS, "smb buf %p len %u\n", smb,
+			 server->ops->calc_smb_size(smb));
+	}
 #endif /* CONFIG_CIFS_DEBUG2 */
 }