From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7AC9750B8C6 for ; Thu, 17 Sep 2026 16:36:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789663015; cv=none; b=b8GFyv0kLd66hM1ERvb1P2EJs42jGZd+lQBmm6IRpSRzIe1V1UX3JbieExFB/DyC9bkuZGVfl2PWWKC1bum2nlUAKrM+0zx6CkuiMe2gK19kZdsufxfPXnq2oNvtkAgT2XnGl4h85SuGqqy/IS+quFgWHMq1OXH3w07vi39w5ck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789663015; c=relaxed/simple; bh=lUeEgB/yc7uaij3yskTDnhsxlCQ0hAaoPnE7vDIGWtw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ekil84ZfXW0tAi5mRlBf+IT45C2AftNuxkVfLQ3FAyMxad4pDByEfmUugaFTcIvohDOn/n5gsam7h9LAe+M+JiUKwo0lNNIcDLlNDy9ePPTYxmd3Y6VExb/HtTZP7Gg+JuDItVPQsgzSNDH0E5Ae6RXQvuL9nmZZ1qB8ShepamQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fLoHLj9C; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fLoHLj9C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D20AD1F00893; Thu, 17 Sep 2026 16:36:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789663014; bh=UgFL9NtH8/YtxxCz7wy0AgI7X6SBIMQl8htPP4XMok0=; h=From:To:Cc:Subject:Date:Reply-To; b=fLoHLj9CVcb6weKORHHNSpOgj4LDkMsNjuNhJuWdoPnsFyKFe6sbtsEm6Pod0wK8f OwoXOvMJA3R6xSRpe05+ge1j3X6Az3C7gtKL5FkH0tdwP0qukVJnmRb7GwgKY0UP9u lwYPZ11L4XRNA1WCzKhcNpF/tIgx+i++lxNmGHqg= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-93099: fs/resctrl: Fix UAF from worker threads when domains are removed Date: Thu, 17 Sep 2026 17:16:16 +0100 Message-ID: <2026091744-CVE-2026-93099-9d2a@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3334; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=oIbF3t2MrZoHOWC/DOOrUEupXFruQ0FuFrdVlzRA0yQ=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBE7U7OE+fuWlocnN5fOmfXjracDA/K43gSPX92H6s 1eB032PdsSyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBERIsZ5lmz5T2ZwudtMXny lW2GTFmLlrJckmaYnzL75TGJmxsTGMv8KxeozDiccWM5GwA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: fs/resctrl: Fix UAF from worker threads when domains are removed The mbm_handle_overflow() and cqm_handle_limbo() workers read event counters and may sleep while doing so. They are scheduled via delayed_work embedded in struct rdt_l3_mon_domain. Architecture allocates and frees these domains from CPU hotplug callbacks under cpus_write_lock(), and the workers acquire cpus_read_lock() to keep the domain alive across their access. A use-after-free can occur when a worker is blocked waiting for cpus_read_lock() while the hotplug core holds cpus_write_lock(): the architecture frees the rdt_l3_mon_domain that contains the worker's work_struct. When the worker unblocks, the container_of() it performs on the embedded work pointer dereferences freed memory. Drop cpus_read_lock() from the workers and instead drain pending and in-flight work synchronously before the architecture can free the domain. Since architecture offlines the domain under cpus_write_lock() after it has been unlinked from the RCU list and a grace period has elapsed, no new work can be scheduled. The cancel only needs to wait out existing work. Drop rdtgroup_mutex during CPU offline around cancel_delayed_work_sync() so that a worker waiting on the mutex can complete before re-pinning the work on a different CPU. When offlining a CPU the architecture may iterate over resources in any order. For example, the MBA control domain may be offlined before or after a corresponding L3 monitor domain. Ensure that resctrl fs cancels the workers no matter what order the architecture offlines the domains. The Linux kernel CVE team has assigned CVE-2026-93099 to this issue. Affected and fixed versions =========================== Issue introduced in 4.14 with commit 24247aeeabe99eab13b798ccccc2dec066dd6f07 and fixed in 7.2.6 with commit b86dbfe4583bf134932a6cc45bf25b12c10a0b2f Issue introduced in 4.14 with commit 24247aeeabe99eab13b798ccccc2dec066dd6f07 and fixed in 7.3-rc1 with commit 2566b5cd6a275c124e8f154fef6e815f92ec8d5c 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-2026-93099 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: fs/resctrl/monitor.c fs/resctrl/rdtgroup.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/b86dbfe4583bf134932a6cc45bf25b12c10a0b2f https://git.kernel.org/stable/c/2566b5cd6a275c124e8f154fef6e815f92ec8d5c