[Webkit-unassigned] [Bug 54877] New: chrome.dll!WebCore::HTMLAreaElement::setFocus ReadAV at NULL (2f8e4496f8ea69da13971f5fddd09753)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=54877

           Summary: chrome.dll!WebCore::HTMLAreaElement::setFocus
                    ReadAV at NULL (2f8e4496f8ea69da13971f5fddd09753)
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: PC
        OS/Version: Windows Vista
            Status: NEW
          Severity: Normal
          Priority: P1
         Component: HTML DOM
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: skylined at chromium.org
                CC: eric at webkit.org


Created an attachment (id=83154)
 --> (https://bugs.webkit.org/attachment.cgi?id=83154&action=review)
Repro

Chromium: http://code.google.com/p/chromium/issues/detail?id=73650

"area" elements can be focussed if they are a link. They can be made a link by setting a "href" attribute to a non-null value. If an area element is focussed, the code checks if its parent element is a "map" element, without verifying if it has a parent element. By creating an area element, setting the href attribute and calling its focus method, we can cause the code to deref a NULL pointer, crashing the renderer.

http://codesearch.google.com/codesearch/p?hl=en#OAMlx_jo-ck/src/third_party/WebKit/Source/WebCore/html/HTMLAreaElement.h&q=HTMLAreaElement&exact_package=chromium&sa=N&cd=1&ct=rc&l=36
class HTMLAreaElement : public HTMLAnchorElement {
<snip>

http://codesearch.google.com/codesearch/p?hl=en#OAMlx_jo-ck/src/third_party/WebKit/Source/WebCore/html/HTMLAnchorElement.cpp&q=HTMLAnchorElement::supportsFocus&exact_package=chromium&sa=N&cd=1&ct=rc&l=73
bool HTMLAnchorElement::supportsFocus() const
{
<snip>
    return isLink() || HTMLElement::supportsFocus();

http://codesearch.google.com/codesearch/p?hl=en#OAMlx_jo-ck/src/third_party/WebKit/Source/WebCore/html/HTMLAreaElement.cpp&q=HTMLAreaElement::setFocus&exact_package=chromium&sa=N&cd=1&ct=rc&l=199
void HTMLAreaElement::setFocus(bool shouldBeFocused)
{
<snip>
    HTMLImageElement* imageElement = this->imageElement();

http://codesearch.google.com/codesearch/p?hl=en#OAMlx_jo-ck/src/third_party/WebKit/Source/WebCore/html/HTMLAreaElement.cpp&q=HTMLAreaElement::imageElement&exact_package=chromium&sa=N&cd=1&ct=rc&l=175

HTMLImageElement* HTMLAreaElement::imageElement() const
{
    Node* mapElement = parentNode();                          /// Might return NULL
    if (!mapElement->hasTagName(mapTag))                      /// Might deref NULL => KaB00m
<snip>

id:             chrome.dll!WebCore::HTMLAreaElement::setFocus ReadAV at NULL (2f8e4496f8ea69da13971f5fddd09753)
description:    Attempt to read from unallocated NULL pointer+0x24 in chrome.dll!WebCore::HTMLAreaElement::setFocus
application:    Chromium 11.0.679.0
stack:          chrome.dll!WebCore::HTMLAreaElement::setFocus
                chrome.dll!WebCore::Document::setFocusedNode
                chrome.dll!WebCore::FocusController::setFocusedNode
                chrome.dll!WebCore::Element::focus
                chrome.dll!WebCore::ElementInternal::focusCallback
                chrome.dll!v8::internal::HandleApiCallHelper<...>
                chrome.dll!v8::internal::Builtin_HandleApiCall
                chrome.dll!v8::internal::Invoke
                chrome.dll!v8::internal::Execution::Call
                ...

Repro:
<script>
  oArea = document.createElement('area');
  oArea.href = 0;
  oArea.focus();
</script>

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