From patchwork Wed Aug 12 07:28:36 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Junjie Cao X-Patchwork-Id: 94983 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8074C5B567 for ; Wed, 12 Aug 2026 05:31:20 +0000 (UTC) Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by mx.groups.io with SMTP id smtpd.msgproc02-g2.1485.1786512676406312614 for ; Tue, 11 Aug 2026 22:31:16 -0700 Authentication-Results: mx.groups.io; dkim=fail reason="dkim: body hash did not verify" header.i=@linux.dev header.s=key1 header.b=GLSbJOpq; spf=pass (domain: linux.dev, ip: 91.218.175.184, mailfrom: junjie.cao@linux.dev) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1786512674; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dBigX+C9Xl0TSpeUaiP/o1MlVCCpMycITKrQwl9RVb8=; b=GLSbJOpqRtJsEBJTkedd7y5T6gsey6PAtA3HoDXTFQmpWYPvCuPBvV/WlhLtkMomoVG21O rGuW/OF8/yjDuucQkWeW2kXHNKyRHnFXMiTCL6gZlSPrFMn1kiaqP5GdFiW2oGvTcjmn/V EF5EbwMv13P2yUSoX+ONxQL3ACWn92c= From: Junjie Cao To: openembedded-core@lists.openembedded.org Cc: paul@pbarker.dev Subject: [OE-core][PATCH v3 3/9] cve-exclusions: set status for CVE-2021-3864 Date: Wed, 12 Aug 2026 02:28:36 -0500 Message-ID: <20260812072842.1176341-4-junjie.cao@linux.dev> In-Reply-To: <20260812072842.1176341-1-junjie.cao@linux.dev> References: <20260812072842.1176341-1-junjie.cao@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT List-Id: X-Webhook-Received: from 45-33-107-173.ip.linodeusercontent.com [45.33.107.173] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Wed, 12 Aug 2026 05:31:20 -0000 X-Groupsio-URL: https://lists.openembedded.org/g/openembedded-core/message/243228 begin_new_exec() resets dumpability to owner-dumpable whenever the real and effective ids match at exec time. A binary exec'd by a setuid program that has already called setuid(0) therefore becomes dumpable as root, and with a relative core_pattern plus an attacker-controlled working directory the resulting core file can be dropped into a privileged directory such as /etc/logrotate.d. Full report with proof of concept: https://www.openwall.com/lists/oss-security/2021/10/20/2 Two fixes were proposed and neither was merged. Waiman Long's patch was judged an ineffective mitigation by Eric W. Biederman and the discussion went quiet in early 2022; Wander Lairson Costa's RFC v2 received design feedback and no v3 followed: https://lore.kernel.org/all/20211221021744.864115-1-longman@redhat.com/ https://lore.kernel.org/all/20211228170910.623156-1-wander@redhat.com/ The flagged logic is unchanged: fs/exec.c still selects TASK_DUMPABLE_OWNER in that case, and fs/coredump.c only applies the suid-safe restriction when dumpable is TASK_DUMPABLE_ROOT, so the dumpable==1 case this CVE describes is not covered. Images that set an absolute path, a pipe or a socket core_pattern are not exploitable. CC: Paul Barker AI-Generated: Uses Claude (claude-opus-5) Signed-off-by: Junjie Cao --- v3: - use "unpatched" instead of "upstream-wontfix"; a NAK of one mitigation is not an upstream wontfix of the issue - drop the "NAKed" wording: the discussion went quiet, it was not formally rejected v2: https://lore.kernel.org/openembedded-core/20260803084827.1348810-1-junjie.cao@linux.dev/ meta/recipes-kernel/linux/cve-exclusion.inc | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/meta/recipes-kernel/linux/cve-exclusion.inc b/meta/recipes-kernel/linux/cve-exclusion.inc index af3576d..ba8e467 100644 --- a/meta/recipes-kernel/linux/cve-exclusion.inc +++ b/meta/recipes-kernel/linux/cve-exclusion.inc @@ -206,3 +206,11 @@ host model, no upstream kernel fix, mitigated by firewall configuration" # https://security-tracker.debian.org/tracker/CVE-2021-3714 CVE_STATUS[CVE-2021-3714] = "unpatched: timing side channel inherent to \ KSM page deduplication, only reachable when KSM is enabled and opted into" + +# Two mitigation attempts, neither merged; the fs/exec.c logic is +# unchanged. An absolute, piped or socket kernel.core_pattern (for +# example systemd-coredump) prevents exploitation. +# https://www.openwall.com/lists/oss-security/2021/10/20/2 +# https://ubuntu.com/security/CVE-2021-3864 +CVE_STATUS[CVE-2021-3864] = "unpatched: no accepted mainline fix, \ +exploitation requires a relative kernel.core_pattern"