lkml.org 
[lkml]   [2022]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 1/2] drm/shmem-helper: Remove errant put in error path
From
On 11/30/22 21:57, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> drm_gem_shmem_mmap() doesn't own this reference, resulting in the GEM
> object getting prematurely freed leading to a later use-after-free.
>
> Link: https://syzkaller.appspot.com/bug?extid=c8ae65286134dd1b800d
> Reported-by: syzbot+c8ae65286134dd1b800d@syzkaller.appspotmail.com
> Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects")
> Cc: stable@vger.kernel.org
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
> drivers/gpu/drm/drm_gem_shmem_helper.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 35138f8a375c..3b7b71391a4c 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -622,10 +622,8 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
> }
>
> ret = drm_gem_shmem_get_pages(shmem);
> - if (ret) {
> - drm_gem_vm_close(vma);
> + if (ret)
> return ret;
> - }
>
> vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
> vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);

AFAICS, the dmabuf mmaping code path needs a similar fix, isn't it?

- /* Drop the reference drm_gem_mmap_obj() acquired.*/
- drm_gem_object_put(obj);
vma->vm_private_data = NULL;

- return dma_buf_mmap(obj->dma_buf, vma, 0);
+ ret = dma_buf_mmap(obj->dma_buf, vma, 0);
+
+ /* Drop the reference drm_gem_mmap_obj() acquired.*/
+ if (!ret)
+ drm_gem_object_put(obj);
+
+ return ret;


--
Best regards,
Dmitry

\
 
 \ /
  Last update: 2022-12-04 21:46    [W:0.028 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site