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drm/radeon: forbid mapping of userptr bo through radeon device file 

Allowing userptr bo which are basicly a list of page from some vma
(so either anonymous page or file backed page) would lead to serious
corruption of kernel structures and counters (because we overwrite
the page->mapping field when mapping buffer).

This will already block if the buffer was populated before anyone does
try to mmap it because then TTM_PAGE_FLAG_SG would be set in in the
ttm_tt flags. But that flag is check before ttm_tt_populate in the ttm
vm fault handler.

So to be safe just add a check to verify_access() callback.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Jérôme Glisse 2016-04-19 09:07:50 -04:00 committed by Alex Deucher
parent 83c5cda2cc
commit b5dcec693f
1 changed files with 2 additions and 0 deletions
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2
drivers/gpu/drm/radeon/radeon_ttm.c
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@ -235,6 +235,8 @@ static int radeon_verify_access(struct ttm_buffer_object *bo, struct file *filp)
{
struct radeon_bo *rbo = container_of(bo, struct radeon_bo, tbo);
if (radeon_ttm_tt_has_userptr(bo->ttm))
return -EPERM;
return drm_vma_node_verify_access(&rbo->gem_base.vma_node, filp);
}