| Message ID | 20201027214922.3566743-1-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/shme-helpers: Fix dma_buf_mmap forwarding bug | expand |
On Tue, 27 Oct 2020 22:49:22 +0100 Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > When we forward an mmap to the dma_buf exporter, they get to own > everything. Unfortunately drm_gem_mmap_obj() overwrote > vma->vm_private_data after the driver callback, wreaking the > exporter complete. This was noticed because vb2_common_vm_close blew > up on mali gpu with panfrost after commit 26d3ac3cb04d > ("drm/shmem-helpers: Redirect mmap for imported dma-buf"). > > Unfortunately drm_gem_mmap_obj also acquires a surplus reference that > we need to drop in shmem helpers, which is a bit of a mislayer > situation. Maybe the entire dma_buf_mmap forwarding should be pulled > into core gem code. > > Note that the only two other drivers which forward mmap in their own > code (etnaviv and exynos) get this somewhat right by overwriting the > gem mmap code. But they seem to still have the leak. This might be a > good excuse to move these drivers over to shmem helpers completely. > > Note to stable team: There's a trivial context conflict with > d693def4fd1c ("drm: Remove obsolete GEM and PRIME callbacks from > struct drm_driver"). I'm assuming it's clear where to put the first > hunk, otherwise I can send a 5.9 version of this. > > Cc: Christian König <christian.koenig@amd.com> > Cc: Sumit Semwal <sumit.semwal@linaro.org> > Cc: Lucas Stach <l.stach@pengutronix.de> > Cc: Russell King <linux+etnaviv@armlinux.org.uk> > Cc: Christian Gmeiner <christian.gmeiner@gmail.com> > Cc: Inki Dae <inki.dae@samsung.com> > Cc: Joonyoung Shim <jy0922.shim@samsung.com> > Cc: Seung-Woo Kim <sw0312.kim@samsung.com> > Cc: Kyungmin Park <kyungmin.park@samsung.com> > Fixes: 26d3ac3cb04d ("drm/shmem-helpers: Redirect mmap for imported dma-buf") > Cc: Boris Brezillon <boris.brezillon@collabora.com> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Gerd Hoffmann <kraxel@redhat.com> > Cc: Rob Herring <robh@kernel.org> > Cc: dri-devel@lists.freedesktop.org > Cc: linux-media@vger.kernel.org > Cc: linaro-mm-sig@lists.linaro.org > Cc: <stable@vger.kernel.org> # v5.9+ > Reported-and-tested-by: piotr.oniszczuk@gmail.com > Cc: piotr.oniszczuk@gmail.com > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > --- > drivers/gpu/drm/drm_gem.c | 4 ++-- > drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++++- > 2 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index 1da67d34e55d..d586068f5509 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -1076,6 +1076,8 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, > */ > drm_gem_object_get(obj); > > + vma->vm_private_data = obj; > + > if (obj->funcs->mmap) { > ret = obj->funcs->mmap(obj, vma); > if (ret) { > @@ -1096,8 +1098,6 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, > vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); > } > > - vma->vm_private_data = obj; > - > return 0; > } > EXPORT_SYMBOL(drm_gem_mmap_obj); > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index fb11df7aced5..8233bda4692f 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -598,8 +598,13 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) > /* Remove the fake offset */ > vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node); > > - if (obj->import_attach) > + if (obj->import_attach) { > + /* 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); > + } > > shmem = to_drm_gem_shmem_obj(obj); >
Am 27.10.20 um 22:49 schrieb Daniel Vetter: > When we forward an mmap to the dma_buf exporter, they get to own > everything. Unfortunately drm_gem_mmap_obj() overwrote > vma->vm_private_data after the driver callback, wreaking the > exporter complete. This was noticed because vb2_common_vm_close blew > up on mali gpu with panfrost after commit 26d3ac3cb04d > ("drm/shmem-helpers: Redirect mmap for imported dma-buf"). > > Unfortunately drm_gem_mmap_obj also acquires a surplus reference that > we need to drop in shmem helpers, which is a bit of a mislayer > situation. Maybe the entire dma_buf_mmap forwarding should be pulled > into core gem code. > > Note that the only two other drivers which forward mmap in their own > code (etnaviv and exynos) get this somewhat right by overwriting the > gem mmap code. But they seem to still have the leak. This might be a > good excuse to move these drivers over to shmem helpers completely. > > Note to stable team: There's a trivial context conflict with > d693def4fd1c ("drm: Remove obsolete GEM and PRIME callbacks from > struct drm_driver"). I'm assuming it's clear where to put the first > hunk, otherwise I can send a 5.9 version of this. > > Cc: Christian König <christian.koenig@amd.com> > Cc: Sumit Semwal <sumit.semwal@linaro.org> > Cc: Lucas Stach <l.stach@pengutronix.de> > Cc: Russell King <linux+etnaviv@armlinux.org.uk> > Cc: Christian Gmeiner <christian.gmeiner@gmail.com> > Cc: Inki Dae <inki.dae@samsung.com> > Cc: Joonyoung Shim <jy0922.shim@samsung.com> > Cc: Seung-Woo Kim <sw0312.kim@samsung.com> > Cc: Kyungmin Park <kyungmin.park@samsung.com> > Fixes: 26d3ac3cb04d ("drm/shmem-helpers: Redirect mmap for imported dma-buf") > Cc: Boris Brezillon <boris.brezillon@collabora.com> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Gerd Hoffmann <kraxel@redhat.com> > Cc: Rob Herring <robh@kernel.org> > Cc: dri-devel@lists.freedesktop.org > Cc: linux-media@vger.kernel.org > Cc: linaro-mm-sig@lists.linaro.org > Cc: <stable@vger.kernel.org> # v5.9+ > Reported-and-tested-by: piotr.oniszczuk@gmail.com > Cc: piotr.oniszczuk@gmail.com > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Acked-by: Christian König <christian.koenig@amd.com> > --- > drivers/gpu/drm/drm_gem.c | 4 ++-- > drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++++- > 2 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index 1da67d34e55d..d586068f5509 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -1076,6 +1076,8 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, > */ > drm_gem_object_get(obj); > > + vma->vm_private_data = obj; > + > if (obj->funcs->mmap) { > ret = obj->funcs->mmap(obj, vma); > if (ret) { > @@ -1096,8 +1098,6 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, > vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); > } > > - vma->vm_private_data = obj; > - > return 0; > } > EXPORT_SYMBOL(drm_gem_mmap_obj); > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index fb11df7aced5..8233bda4692f 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -598,8 +598,13 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) > /* Remove the fake offset */ > vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node); > > - if (obj->import_attach) > + if (obj->import_attach) { > + /* 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); > + } > > shmem = to_drm_gem_shmem_obj(obj); >
On Wed, Oct 28, 2020 at 09:44:15AM +0100, Boris Brezillon wrote: > On Tue, 27 Oct 2020 22:49:22 +0100 > Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > > When we forward an mmap to the dma_buf exporter, they get to own > > everything. Unfortunately drm_gem_mmap_obj() overwrote > > vma->vm_private_data after the driver callback, wreaking the > > exporter complete. This was noticed because vb2_common_vm_close blew > > up on mali gpu with panfrost after commit 26d3ac3cb04d > > ("drm/shmem-helpers: Redirect mmap for imported dma-buf"). > > > > Unfortunately drm_gem_mmap_obj also acquires a surplus reference that > > we need to drop in shmem helpers, which is a bit of a mislayer > > situation. Maybe the entire dma_buf_mmap forwarding should be pulled > > into core gem code. > > > > Note that the only two other drivers which forward mmap in their own > > code (etnaviv and exynos) get this somewhat right by overwriting the > > gem mmap code. But they seem to still have the leak. This might be a > > good excuse to move these drivers over to shmem helpers completely. > > > > Note to stable team: There's a trivial context conflict with > > d693def4fd1c ("drm: Remove obsolete GEM and PRIME callbacks from > > struct drm_driver"). I'm assuming it's clear where to put the first > > hunk, otherwise I can send a 5.9 version of this. > > > > Cc: Christian König <christian.koenig@amd.com> > > Cc: Sumit Semwal <sumit.semwal@linaro.org> > > Cc: Lucas Stach <l.stach@pengutronix.de> > > Cc: Russell King <linux+etnaviv@armlinux.org.uk> > > Cc: Christian Gmeiner <christian.gmeiner@gmail.com> > > Cc: Inki Dae <inki.dae@samsung.com> > > Cc: Joonyoung Shim <jy0922.shim@samsung.com> > > Cc: Seung-Woo Kim <sw0312.kim@samsung.com> > > Cc: Kyungmin Park <kyungmin.park@samsung.com> > > Fixes: 26d3ac3cb04d ("drm/shmem-helpers: Redirect mmap for imported dma-buf") > > Cc: Boris Brezillon <boris.brezillon@collabora.com> > > Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> Patch pushed to drm-misc-fixes, thanks for taking a look. -Daniel > > > Cc: Thomas Zimmermann <tzimmermann@suse.de> > > Cc: Gerd Hoffmann <kraxel@redhat.com> > > Cc: Rob Herring <robh@kernel.org> > > Cc: dri-devel@lists.freedesktop.org > > Cc: linux-media@vger.kernel.org > > Cc: linaro-mm-sig@lists.linaro.org > > Cc: <stable@vger.kernel.org> # v5.9+ > > Reported-and-tested-by: piotr.oniszczuk@gmail.com > > Cc: piotr.oniszczuk@gmail.com > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > > --- > > drivers/gpu/drm/drm_gem.c | 4 ++-- > > drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++++- > > 2 files changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > > index 1da67d34e55d..d586068f5509 100644 > > --- a/drivers/gpu/drm/drm_gem.c > > +++ b/drivers/gpu/drm/drm_gem.c > > @@ -1076,6 +1076,8 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, > > */ > > drm_gem_object_get(obj); > > > > + vma->vm_private_data = obj; > > + > > if (obj->funcs->mmap) { > > ret = obj->funcs->mmap(obj, vma); > > if (ret) { > > @@ -1096,8 +1098,6 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, > > vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); > > } > > > > - vma->vm_private_data = obj; > > - > > return 0; > > } > > EXPORT_SYMBOL(drm_gem_mmap_obj); > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > > index fb11df7aced5..8233bda4692f 100644 > > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > > @@ -598,8 +598,13 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) > > /* Remove the fake offset */ > > vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node); > > > > - if (obj->import_attach) > > + if (obj->import_attach) { > > + /* 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); > > + } > > > > shmem = to_drm_gem_shmem_obj(obj); > > >
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 1da67d34e55d..d586068f5509 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1076,6 +1076,8 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, */ drm_gem_object_get(obj); + vma->vm_private_data = obj; + if (obj->funcs->mmap) { ret = obj->funcs->mmap(obj, vma); if (ret) { @@ -1096,8 +1098,6 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); } - vma->vm_private_data = obj; - return 0; } EXPORT_SYMBOL(drm_gem_mmap_obj); diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index fb11df7aced5..8233bda4692f 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -598,8 +598,13 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) /* Remove the fake offset */ vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node); - if (obj->import_attach) + if (obj->import_attach) { + /* 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); + } shmem = to_drm_gem_shmem_obj(obj);
When we forward an mmap to the dma_buf exporter, they get to own everything. Unfortunately drm_gem_mmap_obj() overwrote vma->vm_private_data after the driver callback, wreaking the exporter complete. This was noticed because vb2_common_vm_close blew up on mali gpu with panfrost after commit 26d3ac3cb04d ("drm/shmem-helpers: Redirect mmap for imported dma-buf"). Unfortunately drm_gem_mmap_obj also acquires a surplus reference that we need to drop in shmem helpers, which is a bit of a mislayer situation. Maybe the entire dma_buf_mmap forwarding should be pulled into core gem code. Note that the only two other drivers which forward mmap in their own code (etnaviv and exynos) get this somewhat right by overwriting the gem mmap code. But they seem to still have the leak. This might be a good excuse to move these drivers over to shmem helpers completely. Note to stable team: There's a trivial context conflict with d693def4fd1c ("drm: Remove obsolete GEM and PRIME callbacks from struct drm_driver"). I'm assuming it's clear where to put the first hunk, otherwise I can send a 5.9 version of this. Cc: Christian König <christian.koenig@amd.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Lucas Stach <l.stach@pengutronix.de> Cc: Russell King <linux+etnaviv@armlinux.org.uk> Cc: Christian Gmeiner <christian.gmeiner@gmail.com> Cc: Inki Dae <inki.dae@samsung.com> Cc: Joonyoung Shim <jy0922.shim@samsung.com> Cc: Seung-Woo Kim <sw0312.kim@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Fixes: 26d3ac3cb04d ("drm/shmem-helpers: Redirect mmap for imported dma-buf") Cc: Boris Brezillon <boris.brezillon@collabora.com> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Gerd Hoffmann <kraxel@redhat.com> Cc: Rob Herring <robh@kernel.org> Cc: dri-devel@lists.freedesktop.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Cc: <stable@vger.kernel.org> # v5.9+ Reported-and-tested-by: piotr.oniszczuk@gmail.com Cc: piotr.oniszczuk@gmail.com Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> --- drivers/gpu/drm/drm_gem.c | 4 ++-- drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++++- 2 files changed, 8 insertions(+), 3 deletions(-)