Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

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Description of problem:

Calls to XFixesGetCursorImage can cause the X server to access released
memory resulting in a crash. The code in the CursorDisplayCursor function
in xfixes/cursor.c stores a pointer to the cursor as follows

  CursorCurrent[pDev->id] = pCursor;

The cursor pointer can get accessed by calling XFixesGetCursorImage even
if the cursor has been released. A suggested fix is to increase the cursor
reference count when storing the pointer. Any currently stored pointer
would need to be released prior to storing the reference

  if (CursorCurrent[pDev->id])
    FreeCursor(CursorCurrent[pDev->id], (Cursor)0);
  CursorCurrent[pDev->id] = RefCursor(pCursor);



Version-Release number of selected component (if applicable):

xorg-x11-server-Xorg-1.17.2-10.el7.x86_64


How reproducible:

Problem was discovered running Google Chrome with VNC.

Steps to Reproduce:
1. start x0vncserver
2. start Google Chrome
3. Move the Google Chrome window using a remove viewer

Actual results:

X server crashes

Expected results:

No crash

Additional info:

The call to XFixesGetCursorImage is being made by the gnome window manager. The call was found in mutter.

Any news when this would be fixed ?

FWIW, the suggested fix works for me (fedora 27, same issue : chromium-browser over x11vnc)

This fix works, and is essential for VMWare Horizon 7 on Linux (Ubuntu16.04), as it causes session shutdown for active users.(In reply to Alan Hourihane from comment #3)
> Any news when this would be fixed ?

After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.