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 6FCE718C33E for ; Fri, 27 Sep 2024 12:41:09 +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=1727440869; cv=none; b=lAqJQekH0riTrmt43gkx4vEtbPDue/Kvl4RWa6v2Vnbz6mlWr6VtfnYjZooOqWCIw/6EajhkruyzVahHSYkajalMQYMXJP1ITdo/vXewCyBp1czBep24MTivMT4GVqtt/2Vi6wjfiIs+TfMqGrF2ydxoJGDWFwXCDVt0GmJ14zs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727440869; c=relaxed/simple; bh=LbjtUc9ykOKUCuTROrcyKTv2sH/K8N6apChQ1PqvOJY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=jW513dmrzoAL1uIrhO74RFO1BbindpOUPE5WUYVVX2PqNAKezPmvfeOjz6oOyO/akFFwatUxFjjYwpCdrDCSUzyKIPEHE2lW2UZNVxWiuWO7jBdso7YCH/vO9Fzshhp6IjDuiFBtavc2mLA5KizpFbEY1jJ7KCb6A/XU0gEbIHw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zo72Rpwm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zo72Rpwm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE0B6C4CEC6; Fri, 27 Sep 2024 12:41:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727440869; bh=LbjtUc9ykOKUCuTROrcyKTv2sH/K8N6apChQ1PqvOJY=; h=From:To:Cc:Subject:Date:Reply-to:From; b=zo72RpwmCwcpObKNrVxxvpR6uo4k0QP6+PbLPbIANdjqPFC7vsUq3TfI2qd2FQXzi yZrscdWnQnQ1MqCENbm30+3hg5alJElxo1EF/rmOmhB1vfVRsqcvGC0uSxrCpVV97j lYowSygchqdVrXmk93f6AQ4Fg7oUn8XSvnQRPloQ= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2024-46839: workqueue: Improve scalability of workqueue watchdog touch Date: Fri, 27 Sep 2024 14:40:07 +0200 Message-ID: <2024092754-CVE-2024-46839-cfab@gregkh> X-Mailer: git-send-email 2.46.2 Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reply-to: , X-Developer-Signature: v=1; a=openpgp-sha256; l=3022; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=LbjtUc9ykOKUCuTROrcyKTv2sH/K8N6apChQ1PqvOJY=; b=owGbwMvMwCRo6H6F97bub03G02pJDGnfls/69thTw9899Hu3QdvmQ+4KabL2zxJWf5u/80zMr ovdR2I2dMSyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBEls5jWDBhioTe/CpXNykr gyO+9m8MpFWXdDHMTynLnBEWvuHHtX2PHh1J5GhhPtseCQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit Description =========== In the Linux kernel, the following vulnerability has been resolved: workqueue: Improve scalability of workqueue watchdog touch On a ~2000 CPU powerpc system, hard lockups have been observed in the workqueue code when stop_machine runs (in this case due to CPU hotplug). This is due to lots of CPUs spinning in multi_cpu_stop, calling touch_nmi_watchdog() which ends up calling wq_watchdog_touch(). wq_watchdog_touch() writes to the global variable wq_watchdog_touched, and that can find itself in the same cacheline as other important workqueue data, which slows down operations to the point of lockups. In the case of the following abridged trace, worker_pool_idr was in the hot line, causing the lockups to always appear at idr_find. watchdog: CPU 1125 self-detected hard LOCKUP @ idr_find Call Trace: get_work_pool __queue_work call_timer_fn run_timer_softirq __do_softirq do_softirq_own_stack irq_exit timer_interrupt decrementer_common_virt * interrupt: 900 (timer) at multi_cpu_stop multi_cpu_stop cpu_stopper_thread smpboot_thread_fn kthread Fix this by having wq_watchdog_touch() only write to the line if the last time a touch was recorded exceeds 1/4 of the watchdog threshold. The Linux kernel CVE team has assigned CVE-2024-46839 to this issue. Affected and fixed versions =========================== Fixed in 5.15.167 with commit 9d08fce64dd7 Fixed in 6.1.110 with commit a2abd35e7dc5 Fixed in 6.6.51 with commit 241bce1c757d Fixed in 6.10.10 with commit da5f374103a1 Fixed in 6.11 with commit 98f887f820c9 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2024-46839 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: kernel/workqueue.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/9d08fce64dd77f42e2361a4818dbc4b50f3c7dad https://git.kernel.org/stable/c/a2abd35e7dc55bf9ed01e2b3481fa78e086d3bf4 https://git.kernel.org/stable/c/241bce1c757d0587721512296952e6bba69631ed https://git.kernel.org/stable/c/da5f374103a1e0881bbd35847dc57b04ac155eb0 https://git.kernel.org/stable/c/98f887f820c993e05a12e8aa816c80b8661d4c87