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7c51846030
Since tweaking i915_vma_compare() we allowed constructors to skip
clearing the ggtt_view believing that we didn't access the unused
members. That, as it turns out, was not entirely true. In particular,
i915_gem_fault() uses
ret = remap_io_mapping(area,
area->vm_start + (vma->ggtt_view.partial.offset << PAGE_SHIFT),
(ggtt->mappable_base + vma->node.start) >> PAGE_SHIFT,
min_t(u64, vma->size, area->vm_end - area->vm_start),
&ggtt->mappable);
i.e. the ggtt_view.partial for both normal and partial views. If we
allowed garbage into the normal vma->ggtt_view and then try userspace
tried to mmap it, we could explode in an unobvious fashion.
Fixes: 7b92c047ba ("drm/i915: Eliminate superfluous i915_ggtt_view_rotated")
Fixes: 3bf4d57519 ("drm/i915: Stop clearing i915_ggtt_view")
Reported-by: Matthew Auld <matthew.william.auld@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170123145245.3972-1-chris@chris-wilson.co.uk
Tested-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.