mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-09 05:31:17 -04:00
9b73bde39c
When using gem with vram carveout the page allocation is managed via
drm_mm. The necessary drm_mm_node is allocated in add_vma, but it is
referenced in msm_gem_object as well. It is freed before the drm_mm_node
has been deallocated leading to use-after-free on every single vram
allocation.
Currently put_iova is called before put_pages in both
msm_gem_free_object and msm_gem_purge:
put_iova -> del_vma -> kfree(vma) // vma holds drm_mm_node
/* later */
put_pages -> put_pages_vram -> drm_mm_remove_node(
msm_obj->vram_node)
// vram_node is a ref to
// drm_mm_node; in _msm_gem_new
It looks like del_vma does nothing else other than freeing the vma
object and removing it from it's list, so delaying the deletion should
be harmless.
This patch splits put_iova in put_iova_spaces and put_iova_vmas, so the
vma can be freed after the mm_node has been deallocated with the mm.
Note: The breaking commit separated the vma allocation from within
msm_gem_object to outside, so the vram_node reference became outside the
msm_gem_object allocation, and freeing order was therefore overlooked.
Fixes: 4b85f7f5cf ("drm/msm: support for an arbitrary number of address spaces")
Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.