From 2e42a17b8f6bc3c0cd69d7556b588011d3ec2394 Mon Sep 17 00:00:00 2001 From: Eliot Courtney Date: Thu, 23 Apr 2026 21:36:52 +0900 Subject: rust: drm: gem: clean up GEM state in init failure case MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, if `drm_gem_object_init` fails, the object is freed without any cleanup. Perform the cleanup in that case. Cc: stable@vger.kernel.org Fixes: c284d3e42338 ("rust: drm: gem: Add GEM object abstraction") Signed-off-by: Eliot Courtney Reviewed-by: Alice Ryhl Reviewed-by: Onur Özkan Link: https://patch.msgid.link/20260423-fix-gem-1-v1-1-e12e35f7bba9@nvidia.com [ Move safety comment closer to unsafe block to avoid a clippy warning. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/drm/gem/mod.rs | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs index 75acda7ba500..01b5bd47a333 100644 --- a/rust/kernel/drm/gem/mod.rs +++ b/rust/kernel/drm/gem/mod.rs @@ -277,8 +277,17 @@ impl Object { // SAFETY: `obj.as_raw()` is guaranteed to be valid by the initialization above. unsafe { (*obj.as_raw()).funcs = &Self::OBJECT_FUNCS }; - // SAFETY: The arguments are all valid per the type invariants. - to_result(unsafe { bindings::drm_gem_object_init(dev.as_raw(), obj.obj.get(), size) })?; + if let Err(err) = + // SAFETY: The arguments are all valid per the type invariants. + to_result(unsafe { + bindings::drm_gem_object_init(dev.as_raw(), obj.obj.get(), size) + }) + { + // SAFETY: `drm_gem_object_init()` initializes the private GEM object state before + // failing, so `drm_gem_private_object_fini()` is the matching cleanup. + unsafe { bindings::drm_gem_private_object_fini(obj.obj.get()) }; + return Err(err); + } // SAFETY: We will never move out of `Self` as `ARef` is always treated as pinned. let ptr = KBox::into_raw(unsafe { Pin::into_inner_unchecked(obj) }); -- cgit v1.2.3 From 0a69ac25bd596d50823d530d0a2004336668c0df Mon Sep 17 00:00:00 2001 From: Eliot Courtney Date: Fri, 1 May 2026 19:49:37 +0900 Subject: rust: drm: fix unsound initialization in drm::Device::new If pinned initialization of drm::Device::Data fails, it calls drm::Device::release via drm_dev_put. This materializes a reference to &drm::Device, but it's not fully constructed yet, because initializing `data` failed. It should not be dropped either. Instead, if pinned initialization fails, make sure drm::Device::release isn't called. Fixes: 2e9fdbe5ec7a ("rust: drm: device: drop_in_place() the drm::Device in release()") Signed-off-by: Eliot Courtney Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260501-fix-drm-1-v2-1-5c4f681837bc@nvidia.com Signed-off-by: Danilo Krummrich --- rust/kernel/drm/device.rs | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs index adbafe8db54d..403fc35353c7 100644 --- a/rust/kernel/drm/device.rs +++ b/rust/kernel/drm/device.rs @@ -119,13 +119,20 @@ impl Device { // compatible `Layout`. let layout = Kmalloc::aligned_layout(Layout::new::()); + // Use a temporary vtable without a `release` callback until `data` is initialized, so + // init failure can release the DRM device without dropping uninitialized fields. + let alloc_vtable = bindings::drm_driver { + release: None, + ..Self::VTABLE + }; + // SAFETY: - // - `VTABLE`, as a `const` is pinned to the read-only section of the compilation, + // - `alloc_vtable` reference remains valid until no longer used, // - `dev` is valid by its type invarants, let raw_drm: *mut Self = unsafe { bindings::__drm_dev_alloc( dev.as_raw(), - &Self::VTABLE, + &alloc_vtable, layout.size(), mem::offset_of!(Self, dev), ) @@ -133,6 +140,10 @@ impl Device { .cast(); let raw_drm = NonNull::new(from_err_ptr(raw_drm)?).ok_or(ENOMEM)?; + // SAFETY: `raw_drm` is a valid pointer to `Self`, given that `__drm_dev_alloc` was + // successful. + let drm_dev = unsafe { Self::into_drm_device(raw_drm) }; + // SAFETY: `raw_drm` is a valid pointer to `Self`. let raw_data = unsafe { ptr::addr_of_mut!((*raw_drm.as_ptr()).data) }; @@ -140,15 +151,14 @@ impl Device { // - `raw_data` is a valid pointer to uninitialized memory. // - `raw_data` will not move until it is dropped. unsafe { data.__pinned_init(raw_data) }.inspect_err(|_| { - // SAFETY: `raw_drm` is a valid pointer to `Self`, given that `__drm_dev_alloc` was - // successful. - let drm_dev = unsafe { Self::into_drm_device(raw_drm) }; - // SAFETY: `__drm_dev_alloc()` was successful, hence `drm_dev` must be valid and the // refcount must be non-zero. unsafe { bindings::drm_dev_put(drm_dev) }; })?; + // SAFETY: `drm_dev` is still private to this function. + unsafe { (*drm_dev).driver = const { &Self::VTABLE } }; + // SAFETY: The reference count is one, and now we take ownership of that reference as a // `drm::Device`. Ok(unsafe { ARef::from_raw(raw_drm) }) -- cgit v1.2.3