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Commit cbe97414 authored by Jonathan Gonzalez V's avatar Jonathan Gonzalez V Committed by Linus Torvalds
Browse files

drm/exynos: call find_vma with the mmap_sem held 



Performing vma lookups without taking the mm->mmap_sem is asking for
trouble.  While doing the search, the vma in question can be modified or
even removed before returning to the caller.  Take the lock (exclusively)
in order to avoid races while iterating through the vmacache and/or
rbtree.

Signed-off-by: default avatarJonathan Gonzalez V <zeus@gnu.org>
Signed-off-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5040573e

drivers/gpu/drm/exynos/exynos_drm_g2d.c

+6 −0
Original line number Diff line number Diff line
@@ -467,14 +467,17 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev, 
		goto err_free;

	}



	down_read(&current->mm->mmap_sem);

	vma = find_vma(current->mm, userptr);

	if (!vma) {

		up_read(&current->mm->mmap_sem);

		DRM_ERROR("failed to get vm region.\n");

		ret = -EFAULT;

		goto err_free_pages;

	}



	if (vma->vm_end < userptr + size) {

		up_read(&current->mm->mmap_sem);

		DRM_ERROR("vma is too small.\n");

		ret = -EFAULT;

		goto err_free_pages;
@@ -482,6 +485,7 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev, 


	g2d_userptr->vma = exynos_gem_get_vma(vma);

	if (!g2d_userptr->vma) {

		up_read(&current->mm->mmap_sem);

		DRM_ERROR("failed to copy vma.\n");

		ret = -ENOMEM;

		goto err_free_pages;
@@ -492,10 +496,12 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev, 
	ret = exynos_gem_get_pages_from_userptr(start & PAGE_MASK,

						npages, pages, vma);

	if (ret < 0) {

		up_read(&current->mm->mmap_sem);

		DRM_ERROR("failed to get user pages from userptr.\n");

		goto err_put_vma;

	}



	up_read(&current->mm->mmap_sem);

	g2d_userptr->pages = pages;



	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);