- strcpy(last_cmd, "hist:");
- strncat(last_cmd, str, MAX_FILTER_STR_VAL - 1 - sizeof("hist:"));
+ /* sizeof() contains the nul byte */
+ len = sizeof(HIST_PREFIX) + strlen(str);
+ kfree(last_cmd);
+ last_cmd = kzalloc(len, GFP_KERNEL);
+ if (!last_cmd)
+ return;
+
+ strcpy(last_cmd, HIST_PREFIX);
+ /* Again, sizeof() contains the nul byte */
+ len -= sizeof(HIST_PREFIX);
+ strncat(last_cmd, str, len);