From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 77D072F49F4; Tue, 18 Nov 2025 07:29:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763450997; cv=none; b=dSV2rtHGWilq9TYu/8/I0l84iJDi/qUhUf5tcaiYtsMtOHQDwrfTJsOS2c7FXJTUSOcIVE1MgUVyt9hPggf7UrCmMD5qJLiY8qQUTpHQmGfp5RwuyhdehOa4wHeV8e209UNweWronc+UE3RCALkJg7Dvw4zvMlienRwINNUA7IU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763450997; c=relaxed/simple; bh=UxiBMwC3uWq0xUu2kIl5lvUXOVp5mKCr8tzUfK2S+FI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=mhl/AX7BMV4Qsyy/ir2B+LeRu/faZUG4JnkxCK8U0aN8bBSuGvnBQAkT3TgyrAt497ZNs0oBZQztCDwdiyOBO4rgdbbLdkk1VZcKtTpYkEwStTS6/p0s81VFyX5qyKOiL7q6glbnsKsnFDtTLCc20Ah8bYPwHAzzZqmSWlzj7UE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QGVf3L35; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QGVf3L35" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54760C116D0; Tue, 18 Nov 2025 07:29:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763450997; bh=UxiBMwC3uWq0xUu2kIl5lvUXOVp5mKCr8tzUfK2S+FI=; h=From:To:Cc:Subject:Date:From; b=QGVf3L35yAMoabWi9OKB06uszFIjJmrDyCFatc7GSYLUcHhUJIbQdBeDtOLjRWSD+ /D/8y1hgjUtwZCfWCymlQKTQpAij8jFUccMk9PENba8ybl+QWxC1lu5pIkT5UJQynu PhjR6RtOa9QANf2uVxTcRbukk2H0oOY3Myjtb90+uGv8JIBxqA3RsktljxqEFAbE8k 1cNfZqiQCc6+kBSbN6PFGl4PMyCPJGrXId5uKOqT00nHzMfCLN/mKynvNoFkUE/HkT vONMSyUHriR1DtyhNR2539aIP6RaFlrBXWcH7aQ9jibS9/j8KEKdq1WMm9+cvX3xnl PlNxujpmsSnGg== From: Philipp Stanner To: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Tamir Duberstein , Christian Schrefl Cc: Philipp Stanner , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2] rust: list: Add unsafe for container_of Date: Tue, 18 Nov 2025 08:28:35 +0100 Message-ID: <20251118072833.196876-3-phasta@kernel.org> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit impl_list_item_mod.rs calls container_of() without unsafe blocks at a couple of places. Since container_of() is an unsafe macro / function, the blocks are strictly necessary. For unknown reasons, that problem was so far not visible and only gets visible once one utilizes the list implementation from within the core crate: error[E0133]: call to unsafe function `core::ptr::mut_ptr::::byte_sub` is unsafe and requires unsafe block --> rust/kernel/lib.rs:252:29 | 252 | let container_ptr = field_ptr.byte_sub(offset).cast::<$Container>(); | ^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function | ::: rust/kernel/drm/jq.rs:98:1 | 98 | / impl_list_item! { 99 | | impl ListItem<0> for BasicItem { using ListLinks { self.links }; } 100 | | } | |_- in this macro invocation | note: an unsafe function restricts its caller, but its body is safe by default --> rust/kernel/list/impl_list_item_mod.rs:216:13 | 216 | unsafe fn view_value(me: *mut $crate::list::ListLinks<$num>) -> *const Self { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ::: rust/kernel/drm/jq.rs:98:1 | 98 | / impl_list_item! { 99 | | impl ListItem<0> for BasicItem { using ListLinks { self.links }; } 100 | | } | |_- in this macro invocation = note: requested on the command line with `-D unsafe-op-in-unsafe-fn` = note: this error originates in the macro `$crate::container_of` which comes from the expansion of the macro `impl_list_item` Add unsafe blocks to container_of to fix the issue. Cc: stable@vger.kernel.org # v6.17+ Fixes: c77f85b347dd ("rust: list: remove OFFSET constants") Suggested-by: Alice Ryhl Signed-off-by: Philipp Stanner --- Changes in v2: - Add unsafes to the list implementation instead of container_of itself. (Alice, Miguel) - Adjust commit message and Fixes: tag. - Add stable-kernel for completeness. --- rust/kernel/list/impl_list_item_mod.rs | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/rust/kernel/list/impl_list_item_mod.rs b/rust/kernel/list/impl_list_item_mod.rs index 202bc6f97c13..7052095efde5 100644 --- a/rust/kernel/list/impl_list_item_mod.rs +++ b/rust/kernel/list/impl_list_item_mod.rs @@ -217,7 +217,7 @@ unsafe fn view_value(me: *mut $crate::list::ListLinks<$num>) -> *const Self { // SAFETY: `me` originates from the most recent call to `prepare_to_insert`, so it // points at the field `$field` in a value of type `Self`. Thus, reversing that // operation is still in-bounds of the allocation. - $crate::container_of!(me, Self, $($field).*) + unsafe { $crate::container_of!(me, Self, $($field).*) } } // GUARANTEES: @@ -242,7 +242,7 @@ unsafe fn post_remove(me: *mut $crate::list::ListLinks<$num>) -> *const Self { // SAFETY: `me` originates from the most recent call to `prepare_to_insert`, so it // points at the field `$field` in a value of type `Self`. Thus, reversing that // operation is still in-bounds of the allocation. - $crate::container_of!(me, Self, $($field).*) + unsafe { $crate::container_of!(me, Self, $($field).*) } } } )*}; @@ -270,9 +270,9 @@ unsafe fn prepare_to_insert(me: *const Self) -> *mut $crate::list::ListLinks<$nu // SAFETY: The caller promises that `me` points at a valid value of type `Self`. let links_field = unsafe { >::view_links(me) }; - let container = $crate::container_of!( + let container = unsafe { $crate::container_of!( links_field, $crate::list::ListLinksSelfPtr, inner - ); + ) }; // SAFETY: By the same reasoning above, `links_field` is a valid pointer. let self_ptr = unsafe { @@ -319,9 +319,9 @@ unsafe fn view_links(me: *const Self) -> *mut $crate::list::ListLinks<$num> { // `ListArc` containing `Self` until the next call to `post_remove`. The value cannot // be destroyed while a `ListArc` reference exists. unsafe fn view_value(links_field: *mut $crate::list::ListLinks<$num>) -> *const Self { - let container = $crate::container_of!( + let container = unsafe { $crate::container_of!( links_field, $crate::list::ListLinksSelfPtr, inner - ); + ) }; // SAFETY: By the same reasoning above, `links_field` is a valid pointer. let self_ptr = unsafe { -- 2.49.0