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glx: don't create implicit GLXWindow if one already exists 

If a GLXMakeCurrent request specifies an X window as its drawable,
__glXGetDrawable will implicitly create a GLXWindow for it. However,
the client may have already explicitly created a GLXWindow for that X
window. If that happens, two __glXDrawableRes resources will be added
to the window.

If the explicitly-created GLXWindow is later destroyed by the client,
DrawableGone will call FreeResourceByType on the X window, but this
will actually free the resource for the implicitly-created GLXWindow,
since that one would be at the head of the list.

Then if the X window is destroyed after that, the resource for the
explicitly-created GLXWindow will be freed. But that GLXWindow was
already destroyed above. This crashes the server when it tries to call
the destroyed GLXWindow's destructor. It also means the
implicitly-created GLXWindow would have been leaked since the
FreeResourceByType call mentioned above skips calling the destructor.

To fix this, if __glXGetDrawable is given an X window, it should check
if there is already a GLXWindow associated with it, and only create an
implicit one if there is not.

Signed-off-by: Erik Kurzinger <ekurzinger@nvidia.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
This commit is contained in:
Erik Kurzinger 2020-12-10 14:24:32 -08:00 committed by Olivier Fourdan
parent 8274dd6643
commit b7a85e44da
1 changed files with 9 additions and 2 deletions
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11
glx/glxcmds.c
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@ -487,8 +487,15 @@ __glXGetDrawable(__GLXcontext * glxc, GLXDrawable drawId, ClientPtr client,
__GLXscreen *pGlxScreen;
int rc;
if (validGlxDrawable(client, drawId, GLX_DRAWABLE_ANY,
DixWriteAccess, &pGlxDraw, &rc)) {
rc = dixLookupResourceByType((void **)&pGlxDraw, drawId,
__glXDrawableRes, client, DixWriteAccess);
if (rc == Success &&
/* If pGlxDraw->drawId == drawId, drawId is a valid GLX drawable.
* Otherwise, if pGlxDraw->type == GLX_DRAWABLE_WINDOW, drawId is
* an X window, but the client has already created a GLXWindow
* associated with it, so we don't want to create another one. */
(pGlxDraw->drawId == drawId ||
pGlxDraw->type == GLX_DRAWABLE_WINDOW)) {
if (glxc != NULL &&
glxc->config != NULL &&
glxc->config != pGlxDraw->config) {