[W] UMR: Uninitialized memory read in cairo_pattern_release_surface {69 occurrences}
        Reading 4 bytes from 0x0013b7b4 (4 bytes at 0x0013b7b4 uninitialized)
        Address 0x0013b7b4 points into a thread's stack 
        Address 0x0013b7b4 is 68 bytes past the start of local variable
'src_attr' in cairo_image_surface_composite
        Thread ID: 0x2e0
        Error location
            cairo_pattern_release_surface
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-pattern.c:1426]
            cairo_image_surface_composite
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-image-surface.c:600]
            fallback_composite
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-surface.c:508]
            cairo_surface_composite
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-surface.c:550]
            composite_trap_region
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-gstate.c:1232]
            cairo_gstate_clip_and_composite_trapezoids
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-gstate.c:1471]
            cairo_gstate_paint
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo-gstate.c:780]
            cairo_paint    [c:\builds\mozilla\gfx\cairo\cairo\src\cairo.c:1221]
            cairo_paint_with_alpha
[c:\builds\mozilla\gfx\cairo\cairo\src\cairo.c:1249]


The code is using src_attr->extras which has not been initialized to anything
and could result in some problems down the road.  I suspect it should just be
set to null in _cairo_image_surface_set_attributes().