1 files changed, 12 insertions, 4 deletions

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 86a9abb9a1ce..d8773dcd83c5 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -570,24 +570,32 @@ __setup("ddebug_query=", ddebug_setup_query);
  * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
  * command text from userspace, parses and executes it.
  */
+#define USER_BUF_PAGE 4096
 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
                                   size_t len, loff_t *offp)
 {
-        char tmpbuf[256];
+        char *tmpbuf;
         int ret;
 
         if (len == 0)
                 return 0;
-        /* we don't check *offp -- multiple writes() are allowed */
-        if (len > sizeof(tmpbuf)-1)
+        if (len > USER_BUF_PAGE - 1) {
+                pr_warn("expected <%d bytes into control\n", USER_BUF_PAGE);
                 return -E2BIG;
-        if (copy_from_user(tmpbuf, ubuf, len))
+        }
+        tmpbuf = kmalloc(len + 1, GFP_KERNEL);
+        if (!tmpbuf)
+                return -ENOMEM;
+        if (copy_from_user(tmpbuf, ubuf, len)) {
+                kfree(tmpbuf);
                 return -EFAULT;
+        }
         tmpbuf[len] = '\0';
         if (verbose)
                 pr_info("read %d bytes from userspace\n", (int)len);
 
         ret = ddebug_exec_query(tmpbuf);
+        kfree(tmpbuf);
         if (ret)
                 return ret;