Thank you for your contribution! Sashiko AI review found 5 potential issue(s) to consider:
Pre-existing issues: - [Critical] TOCTOU race on `srf->res.guest_memory_bo` leading to a NULL pointer dereference in `drm_gem_handle_create`. - [Critical] Lockless accesses to `guest_memory_bo` after releasing `cmdbuf_mutex` can lead to a Use-After-Free or NULL pointer dereference. - [High] Leaked DRM handle on error paths in `vmw_gb_surface_reference_internal` when processing a PRIME file descriptor. - [High] GEM handle leak in `vmw_gb_surface_define_internal` when initialization fails after handle creation. - [Medium] The function `vmw_gb_surface_reference_internal` fails to populate the `buffer_byte_stride` field in the extended reply structure. -- --- Patch [1]: [PATCH] drm/vmwgfx: return an error when a shared GB surface has no backup buffer --- commit 6bbaf49225562d900a468ed3b35d8995cea03c99 Author: Aldo Ariel Panzardo <[email protected]> drm/vmwgfx: return an error when a shared GB surface has no backup buffer This commit fixes a missing error assignment in vmw_gb_surface_reference_internal() when a shared GB surface lacks a backup buffer. By returning -EINVAL instead of 0, it prevents the ioctl from returning uninitialized stack memory to userspace. > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c > b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c > index bd0563741e89d..014f674744ac3 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c > @@ -1720,6 +1720,7 @@ vmw_gb_surface_reference_internal(struct drm_device > *dev, > srf = &user_srf->srf; > if (!srf->res.guest_memory_bo) { > DRM_ERROR("Shared GB surface is missing a backup buffer.\n"); > + ret = -EINVAL; > goto out_bad_resource; > } [Severity: Critical] This is a pre-existing issue, but does this lockless check create a TOCTOU race? If a concurrent thread detaches the backup buffer and sets guest_memory_bo to NULL under cmdbuf_mutex, the lockless check here might pass, but a NULL pointer would then be dereferenced in drm_gem_handle_create(): drivers/gpu/drm/vmwgfx/vmwgfx_surface.c:vmw_gb_surface_reference_internal() { ... mutex_lock(&dev_priv->cmdbuf_mutex); ret = drm_gem_handle_create(file_priv, &srf->res.guest_memory_bo->tbo.base, &backup_handle); mutex_unlock(&dev_priv->cmdbuf_mutex); ... } [Severity: High] This isn't a bug introduced by this patch, but does taking this error path leak a DRM handle? When handle_type == DRM_VMW_HANDLE_PRIME, vmw_surface_handle_reference() adds a reference to the file's handle table. The cleanup path at out_bad_resource drops the object reference but doesn't remove the newly created handle from the file: drivers/gpu/drm/vmwgfx/vmwgfx_surface.c:vmw_gb_surface_reference_internal() { ... out_bad_resource: ttm_base_object_unref(&base); return ret; } > metadata = &srf->metadata; [Severity: Critical] This is a pre-existing issue, but are there unsafe lockless accesses to guest_memory_bo later in this function? After releasing cmdbuf_mutex, the function populates mapping handles and sizes by locklessly dereferencing srf->res.guest_memory_bo: drivers/gpu/drm/vmwgfx/vmwgfx_surface.c:vmw_gb_surface_reference_internal() { ... rep->crep.buffer_map_handle = drm_vma_node_offset_addr( &srf->res.guest_memory_bo->tbo.base.vma_node); rep->crep.buffer_size = srf->res.guest_memory_bo->tbo.base.size; ... } Could this lead to a NULL pointer dereference or Use-After-Free if another thread detaches or frees the backup buffer concurrently? [Severity: Medium] This isn't a bug introduced by this patch, but does this function fail to populate the buffer_byte_stride field in the extended reply structure? drivers/gpu/drm/vmwgfx/vmwgfx_surface.c:vmw_gb_surface_reference_internal() { ... rep->creq.version = drm_vmw_gb_surface_v1; rep->creq.svga3d_flags_upper_32_bits = SVGA3D_FLAGS_UPPER_32(metadata->flags); rep->creq.multisample_pattern = metadata->multisample_pattern; rep->creq.quality_level = metadata->quality_level; rep->creq.must_be_zero = 0; ... } [Severity: High] This is a pre-existing issue, but does vmw_gb_surface_define_internal() leak a GEM handle when initialization fails? If any initialization fails after vmw_gem_object_create_with_handle() successfully allocates a GEM buffer object and registers backup_handle, the cleanup path fails to call drm_gem_handle_delete(): drivers/gpu/drm/vmwgfx/vmwgfx_surface.c:vmw_gb_surface_define_internal() { ... ret = vmw_gem_object_create_with_handle(dev_priv, file_priv, res->guest_memory_size, &backup_handle, &res->guest_memory_bo); } if (unlikely(ret != 0)) { vmw_resource_unreference(&res); goto out_unlock; } ... out_unlock: vmw_resource_unreference(&tmp); vmw_resource_unreference(&res); return ret; } -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
