1208856 - Possible bad null-check in sdnAccessible::get_computedStyle()

Status: RESOLVED DUPLICATE of bug 1208900

(Core :: Disability Access APIs, defect)

Description

[Stefan Sitter [:ssitter]]

From "Static Analysis of Mozilla Thunderbird's Code by PVS-Studio" <http://www.viva64.com/en/b/0347/>:

PVS-Studio's diagnostic message: V522 Dereferencing of the null pointer 'aStyleValues' might take place. sdnaccessible.cpp 252

STDMETHODIMP sdnAccessible::get_computedStyle(
                   BSTR __RPC_FAR* aStyleProperties,
                   BSTR __RPC_FAR* aStyleValues,
                   unsigned short __RPC_FAR* aNumStyleProperties)
{
  if (!aStyleProperties || aStyleValues || !aNumStyleProperties)
    return E_INVALIDARG;
  ....
  aStyleValues[realIndex] = ::SysAllocString(value.get());
  ....
}

Find the rogue.

The analyzer has detected a null pointer dereferencing issue. When implementing the check, the programmer forgot to add "!" before "aStyleValues". The subsequent code gets control only when this pointer equals zero, and dereferences it.