From 9ef8d83e8e25d5f1811b3a38eb1484f85f64296c Mon Sep 17 00:00:00 2001 From: Zack Rusin Date: Sat, 11 Feb 2023 00:05:14 -0500 Subject: [PATCH] drm/vmwgfx: Do not drop the reference to the handle too soon v3: Fix vmw_user_bo_lookup which was also dropping the gem reference before the kernel was done with buffer depending on userspace doing the right thing. Same bug, different spot. It is possible for userspace to predict the next buffer handle and to destroy the buffer while it's still used by the kernel. Delay dropping the internal reference on the buffers until kernel is done with them. Instead of immediately dropping the gem reference in vmw_user_bo_lookup and vmw_gem_object_create_with_handle let the callers decide when they're ready give the control back to userspace. Also fixes the second usage of vmw_gem_object_create_with_handle in vmwgfx_surface.c which wasn't grabbing an explicit reference to the gem object which could have been destroyed by the userspace on the owning surface at any point. Signed-off-by: Zack Rusin Fixes: 8afa13a0583f ("drm/vmwgfx: Implement DRIVER_GEM") Reviewed-by: Martin Krastev Reviewed-by: Maaz Mombasawala Link: https://patchwork.freedesktop.org/patch/msgid/20230211050514.2431155-1-zack@kde.org --- drivers/gpu/drm/vmwgfx/vmwgfx_bo.c | 8 +++++--- drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 2 ++ drivers/gpu/drm/vmwgfx/vmwgfx_gem.c | 4 ++-- drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 4 +++- drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c | 1 + drivers/gpu/drm/vmwgfx/vmwgfx_shader.c | 1 + drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 10 ++++++---- 7 files changed, 20 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c index 7a00314882a311..82094c137855b9 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c @@ -500,6 +500,7 @@ static int vmw_user_bo_synccpu_release(struct drm_file *filp, ttm_bo_put(&vmw_bo->tbo); } + drm_gem_object_put(&vmw_bo->tbo.base); return ret; } @@ -540,6 +541,7 @@ int vmw_user_bo_synccpu_ioctl(struct drm_device *dev, void *data, ret = vmw_user_bo_synccpu_grab(vbo, arg->flags); vmw_bo_unreference(&vbo); + drm_gem_object_put(&vbo->tbo.base); if (unlikely(ret != 0)) { if (ret == -ERESTARTSYS || ret == -EBUSY) return -EBUSY; @@ -596,7 +598,7 @@ int vmw_bo_unref_ioctl(struct drm_device *dev, void *data, * struct vmw_bo should be placed. * Return: Zero on success, Negative error code on error. * - * The vmw buffer object pointer will be refcounted. + * The vmw buffer object pointer will be refcounted (both ttm and gem) */ int vmw_user_bo_lookup(struct drm_file *filp, u32 handle, @@ -613,7 +615,6 @@ int vmw_user_bo_lookup(struct drm_file *filp, *out = to_vmw_bo(gobj); ttm_bo_get(&(*out)->tbo); - drm_gem_object_put(gobj); return 0; } @@ -693,7 +694,8 @@ int vmw_dumb_create(struct drm_file *file_priv, ret = vmw_gem_object_create_with_handle(dev_priv, file_priv, args->size, &args->handle, &vbo); - + /* drop reference from allocate - handle holds it now */ + drm_gem_object_put(&vbo->tbo.base); return ret; } diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index 6d1b46c23719bc..6b9aa2b4ef54ad 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -1165,6 +1165,7 @@ static int vmw_translate_mob_ptr(struct vmw_private *dev_priv, vmw_bo_placement_set(vmw_bo, VMW_BO_DOMAIN_MOB, VMW_BO_DOMAIN_MOB); ret = vmw_validation_add_bo(sw_context->ctx, vmw_bo); ttm_bo_put(&vmw_bo->tbo); + drm_gem_object_put(&vmw_bo->tbo.base); if (unlikely(ret != 0)) return ret; @@ -1221,6 +1222,7 @@ static int vmw_translate_guest_ptr(struct vmw_private *dev_priv, VMW_BO_DOMAIN_GMR | VMW_BO_DOMAIN_VRAM); ret = vmw_validation_add_bo(sw_context->ctx, vmw_bo); ttm_bo_put(&vmw_bo->tbo); + drm_gem_object_put(&vmw_bo->tbo.base); if (unlikely(ret != 0)) return ret; diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c index 51bd1f8c5cc451..d6baf73a64589a 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c @@ -133,8 +133,6 @@ int vmw_gem_object_create_with_handle(struct vmw_private *dev_priv, (*p_vbo)->tbo.base.funcs = &vmw_gem_object_funcs; ret = drm_gem_handle_create(filp, &(*p_vbo)->tbo.base, handle); - /* drop reference from allocate - handle holds it now */ - drm_gem_object_put(&(*p_vbo)->tbo.base); out_no_bo: return ret; } @@ -161,6 +159,8 @@ int vmw_gem_object_create_ioctl(struct drm_device *dev, void *data, rep->map_handle = drm_vma_node_offset_addr(&vbo->tbo.base.vma_node); rep->cur_gmr_id = handle; rep->cur_gmr_offset = 0; + /* drop reference from allocate - handle holds it now */ + drm_gem_object_put(&vbo->tbo.base); out_no_bo: return ret; } diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c index 8659de9d23f354..84d6380b98950c 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c @@ -1725,8 +1725,10 @@ static struct drm_framebuffer *vmw_kms_fb_create(struct drm_device *dev, err_out: /* vmw_user_lookup_handle takes one ref so does new_fb */ - if (bo) + if (bo) { vmw_bo_unreference(&bo); + drm_gem_object_put(&bo->tbo.base); + } if (surface) vmw_surface_unreference(&surface); diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c b/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c index 7bcda29a2897dd..8d171d71cb8a73 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c @@ -458,6 +458,7 @@ int vmw_overlay_ioctl(struct drm_device *dev, void *data, ret = vmw_overlay_update_stream(dev_priv, buf, arg, true); vmw_bo_unreference(&buf); + drm_gem_object_put(&buf->tbo.base); out_unlock: mutex_unlock(&overlay->mutex); diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c b/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c index 6b8e984695ed0d..e7226db8b24248 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c @@ -810,6 +810,7 @@ static int vmw_shader_define(struct drm_device *dev, struct drm_file *file_priv, num_output_sig, tfile, shader_handle); out_bad_arg: vmw_bo_unreference(&buffer); + drm_gem_object_put(&buffer->tbo.base); return ret; } diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c index 9d4ae9623a0088..5db403ee8261d3 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c @@ -686,7 +686,7 @@ static void vmw_user_surface_base_release(struct ttm_base_object **p_base) container_of(base, struct vmw_user_surface, prime.base); struct vmw_resource *res = &user_srf->srf.res; - if (base->shareable && res && res->guest_memory_bo) + if (res->guest_memory_bo) drm_gem_object_put(&res->guest_memory_bo->tbo.base); *p_base = NULL; @@ -867,7 +867,11 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data, goto out_unlock; } vmw_bo_reference(res->guest_memory_bo); - drm_gem_object_get(&res->guest_memory_bo->tbo.base); + /* + * We don't expose the handle to the userspace and surface + * already holds a gem reference + */ + drm_gem_handle_delete(file_priv, backup_handle); } tmp = vmw_resource_reference(&srf->res); @@ -1571,8 +1575,6 @@ vmw_gb_surface_define_internal(struct drm_device *dev, drm_vma_node_offset_addr(&res->guest_memory_bo->tbo.base.vma_node); rep->buffer_size = res->guest_memory_bo->tbo.base.size; rep->buffer_handle = backup_handle; - if (user_srf->prime.base.shareable) - drm_gem_object_get(&res->guest_memory_bo->tbo.base); } else { rep->buffer_map_handle = 0; rep->buffer_size = 0;