From nobody Wed Feb 18 15:22:29 2026 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4fGKxy17Ttz6SLsL for ; Wed, 18 Feb 2026 15:22:30 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R12" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4fGKxx4ktsz40JD for ; Wed, 18 Feb 2026 15:22:29 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1771428149; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=UAR3XV70cvNayOolXIkDfb92SH4G2eZwUKfEW4Vb5hQ=; b=KGsGpeUbc5bYetQIS5LRVrIW8wemBlQr9SIL89qQwaQN8OufBD/tBE/wiY6NWD1saeql3i kr/o4MAcTyLwSPiG5uI54Spdf+5JBj8glG/wbBT1lmkNkUu4Mc3Ud+83HIt6GwhfrpbcjL gS8Bou7b2q+RTUGYtmD9uFNOaGvkUR+zV71oGQc89w8NKwafPJ59tIG7f7GBuKUuNXMOD5 OMELj+7ERHE6dJpnHYdmFbA5dnVn9RhZWhYIuIoawPrCsxLnjcWrtsY/EjTpjl5aTTgacP C/3mMuJnu6K8G4C3nagIwvgbfHXWenQQnk7QsI0KrWhDtVFSXBQzqUPFOnKLoQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1771428149; a=rsa-sha256; cv=none; b=VMqyAcclOiSMmRvC9jsdCtIPPyMLSlYjGfofWdKPzE9i8gvBT39Pga/dnN8gx53inSDM3U W/s76hfiXrmb8Em7DlR4QyKSrZJk6ZFKlR1+YnUZZqbm0oqkQb8bvdKcV8vLBawkMyGt26 NstFBV96kxi9/cXOJwlIujPRbD2zBd9iOgMtQArNAhoVdpPIcxil0I+cgV4hNrVFMnEMPK hAt8Gnu2eFALEOUwF9JMStduRJNA2DoyHGkPWsFJTpY3v0BNimz+ksbMAlqRmENqBwBtDB upD2Xg0EB1t4O0Yjkes/pkAp/apiIO7aNTcMOqZeeP9TlImHg5V/MTesBwAMig== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1771428149; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=UAR3XV70cvNayOolXIkDfb92SH4G2eZwUKfEW4Vb5hQ=; b=WTtTqpC80ixhmrnc7p/mPjvA9Gl9EDRV3CEfBP6aV+LLsY2STXemofqfc/QUOx1xeD3zkm zjSnoTLdR3lIlI0vYp0wm+rRh4fS5DobOMv7fDbsg1ekF6Zrl8vL5bO763DXoFWiRTjOLQ gzup5aUGMyOL8NX8XjV5Wq3OuMqvGgIasWbpMF5CvQrXXVHalR8765cIiVjDvGbvXi2sbB KugTQb5CkTZfuP/HgcEXrVJZsivjJIjFVR8rvZ8RSxftuJ6fWy0ueyNdRN1Mb1DML0WjXa H5BMou9ElbltWm+sp5/LMHUdfcJNkylhTA+dAAdF9/fZnDwT3k9fui4OXFCH5Q== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4fGKxx0yMnz120d for ; Wed, 18 Feb 2026 15:22:29 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 24430 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Wed, 18 Feb 2026 15:22:29 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Ed Maste Subject: git: b20883e8210e - main - mitigations.7: Describe LASS List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: emaste X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: b20883e8210eb30c8ffba467c4bc9fce89bde6c4 Auto-Submitted: auto-generated Date: Wed, 18 Feb 2026 15:22:29 +0000 Message-Id: <6995d935.24430.40fd2e67@gitrepo.freebsd.org> The branch main has been updated by emaste: URL: https://cgit.FreeBSD.org/src/commit/?id=b20883e8210eb30c8ffba467c4bc9fce89bde6c4 commit b20883e8210eb30c8ffba467c4bc9fce89bde6c4 Author: Ed Maste AuthorDate: 2026-02-13 20:31:51 +0000 Commit: Ed Maste CommitDate: 2026-02-18 15:22:14 +0000 mitigations.7: Describe LASS Reviewed by: kib, markj Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D55281 --- share/man/man7/mitigations.7 | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/share/man/man7/mitigations.7 b/share/man/man7/mitigations.7 index c3c6ab55c480..37a81986e372 100644 --- a/share/man/man7/mitigations.7 +++ b/share/man/man7/mitigations.7 @@ -335,8 +335,17 @@ Another feature prevents unintended reads from or writes to user space memory from the kernel. This also provides effective protection against NULL pointer dereferences from kernel. +An additional mechanism, +Linear Address Space Separation (LASS), is available on some amd64 machines. +LASS prevents user-mode applications from accessing kernel-mode memory, +and the kernel from unsanctioned access to userspace memory. +Unlike page table-based permission controls, LASS is based only on address +values. +As a consequence of enforcing this separation in hardware, LASS also provides +mitigation against certain speculative-execution side-channel attacks. .Bl -column -offset indent "Architecture" "Feature" "Access Type Prevented" .It Sy Architecture Ta Sy Feature Ta Sy Access Type Prevented +.It amd64 Ta LASS Ta All .It amd64 Ta SMAP Ta Read / Write .It amd64 Ta SMEP Ta Execute .It arm64 Ta PAN Ta Read / Write @@ -345,8 +354,12 @@ kernel. .It riscv Ta - Ta Execute .El .Pp -These features are automatically used by the kernel. -There is no user-facing configuration. +Most of these features are automatically used by the kernel, +with no user-facing configuration. +LASS is controlled by the +.Va hw.lass +loader tunable. +It is enabled by default, when available. .\" .Ss Capsicum Capsicum is a lightweight OS capability and sandbox framework.