check_nt: Fixes NULL pointer dereference

Thanks to Vaclav Ovsik for reporting the issue and providing a fix

2 files changed, 14 insertions, 3 deletions

diff --git a/THANKS.in b/THANKS.in
index fdebd656..ae4ea943 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -280,3 +280,4 @@ Alex Bradley
 Brian De Wolf
 Richard Leitner
 Diego Elio Pettenò
+Vaclav Ovsik
diff --git a/plugins/check_nt.c b/plugins/check_nt.c
index 89c4d8d3..52bbd1c5 100644
--- a/plugins/check_nt.c
+++ b/plugins/check_nt.c
@@ -94,6 +94,7 @@ int main(int argc, char **argv){
         char *description=NULL,*counter_unit = NULL;
         char *minval = NULL, *maxval = NULL, *errcvt = NULL;
         char *fds=NULL, *tds=NULL;
+        char *numstr;
 
         double total_disk_space=0;
         double free_disk_space=0;
@@ -265,7 +266,10 @@ int main(int argc, char **argv){
                         xasprintf(&send_buffer,"%s&%u&%s&%s", req_password,(vars_to_check==CHECK_SERVICESTATE)?5:6,
                                                          (show_all==TRUE) ? "ShowAll" : "ShowFail",value_list);
                         fetch_data (server_address, server_port, send_buffer);
-                        return_code=atoi(strtok(recv_buffer,"&"));
+                        numstr = strtok(recv_buffer,"&");
+                        if (numstr == NULL)
+                                die(STATE_UNKNOWN, _("could not fetch information from server\n"));
+                        return_code=atoi(numstr);
                         temp_string=strtok(NULL,"&");
                         output_message = strdup (temp_string);
                 }
@@ -275,8 +279,14 @@ int main(int argc, char **argv){
 
                 xasprintf(&send_buffer,"%s&7", req_password);
                 fetch_data (server_address, server_port, send_buffer);
-                mem_commitLimit=atof(strtok(recv_buffer,"&"));
-                mem_commitByte=atof(strtok(NULL,"&"));
+                numstr = strtok(recv_buffer,"&");
+                if (numstr == NULL)
+                        die(STATE_UNKNOWN, _("could not fetch information from server\n"));
+                mem_commitLimit=atof(numstr);
+                numstr = strtok(NULL,"&");
+                if (numstr == NULL)
+                        die(STATE_UNKNOWN, _("could not fetch information from server\n"));
+                mem_commitByte=atof(numstr);
                 percent_used_space = (mem_commitByte / mem_commitLimit) * 100;
                 warning_used_space = ((float)warning_value / 100) * mem_commitLimit;
                 critical_used_space = ((float)critical_value / 100) * mem_commitLimit;