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rootless: Ensure gResizeDeathPix is stored in locally-managed memory rather than re-using the implementation's backing store 

The implementation owns the pointer during RootlessStopDrawing and
RootlessStartDrawing and is free to (does) change it.  Rootless
cannot assume ownership of this memory region.  This is possibly
the cause of some hard to diagnose crashes in XQuartz over the
years.

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
This commit is contained in:
Jeremy Huddleston Sequoia 2023-01-02 22:33:00 -08:00
parent f71ef2f02f
commit 65ee3248f5
1 changed files with 5 additions and 15 deletions
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20
miext/rootless/rootlessWindow.c
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@ -1012,7 +1012,12 @@ StartFrameResize(WindowPtr pWin, Bool gravity,
} }
else if (gravity) { else if (gravity) {
/* The general case. Just copy everything. */ /* The general case. Just copy everything. */
need_window_source = TRUE;
}
/* If necessary, create a source pixmap pointing at the current
window bits. */
if (need_window_source) {
RootlessStartDrawing(pWin); RootlessStartDrawing(pWin);
gResizeDeathBits = xallocarray(winRec->bytesPerRow, winRec->height); gResizeDeathBits = xallocarray(winRec->bytesPerRow, winRec->height);
@ -1054,21 +1059,6 @@ StartFrameResize(WindowPtr pWin, Bool gravity,
RootlessStartDrawing(pWin); RootlessStartDrawing(pWin);
/* If necessary, create a source pixmap pointing at the current
window bits. */
if (need_window_source) {
gResizeDeathBounds[0] = (BoxRec) {
oldX, oldY, oldX2, oldY2};
gResizeDeathPix[0]
= GetScratchPixmapHeader(pScreen, oldW, oldH,
winRec->win->drawable.depth,
winRec->win->drawable.bitsPerPixel,
winRec->bytesPerRow, winRec->pixelData);
SetPixmapBaseToScreen(gResizeDeathPix[0], oldX, oldY);
}
/* Use custom CopyWindow when moving gravity bits around /* Use custom CopyWindow when moving gravity bits around
ResizeWindow assumes the old window contents are in the same ResizeWindow assumes the old window contents are in the same
pixmap, but here they're in deathPix instead. */ pixmap, but here they're in deathPix instead. */