Messages in this thread | | | Date | Mon, 30 May 2022 09:26:13 +0200 | Subject | Re: [PATCH] drm/prime: Ensure mmap offset is initialized | From | Thomas Zimmermann <> |
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Hi
Am 29.05.22 um 18:29 schrieb Rob Clark: > From: Rob Clark <robdclark@chromium.org> > > If a GEM object is allocated, and then exported as a dma-buf fd which is > mmap'd before or without the GEM buffer being directly mmap'd, the > vma_node could be unitialized. This leads to a situation where the CPU > mapping is not correctly torn down in drm_vma_node_unmap().
Which drivers are affected by this problem?
I checked several drivers and most appear to be initializing the offset during object construction, such as GEM SHMEM. [1] TTM-based drivers also seem unaffected. [2]
From a quick grep, only etnaviv, msm and omapdrm appear to be affected? They only seem to run drm_gem_create_mmap_offset() from their ioctl-handling code.
If so, I'd say it's preferable to fix these drivers and put a drm_WARN_ONCE() into drm_gem_prime_mmap().
Best regards Thomas
[1] https://elixir.bootlin.com/linux/v5.18/source/drivers/gpu/drm/drm_gem_shmem_helper.c#L85 [2] https://elixir.bootlin.com/linux/v5.18/source/drivers/gpu/drm/ttm/ttm_bo.c#L1002
> > Fixes: e5516553999f ("drm: call drm_gem_object_funcs.mmap with fake offset") > Signed-off-by: Rob Clark <robdclark@chromium.org> > --- > Note, it's possible the issue existed in some related form prior to the > commit tagged with Fixes. > > drivers/gpu/drm/drm_prime.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index e3f09f18110c..849eea154dfc 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -716,6 +716,11 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) > struct file *fil; > int ret; > > + /* Ensure that the vma_node is initialized: */ > + ret = drm_gem_create_mmap_offset(obj); > + if (ret) > + return ret; > + > /* Add the fake offset */ > vma->vm_pgoff += drm_vma_node_start(&obj->vma_node); >
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev [unhandled content-type:application/pgp-signature] | |