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 2F4CF569F04 for ; Wed, 9 Sep 2026 16:13:41 +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=1788970422; cv=none; b=DIlKlypmwNJRFOsJY12/yryNA0WYaog2FN8jJaCoNKPvM6AUTOgURhvX+k4T0zFACIm1SnD0gW5Pil8p8x55r9oP5zkUHICbAEoLD/tcqGZHo8mS6Ji4l8JBqd1NtwHukqG7H62/690JUhANumFoPO6qvK4ZPbAEsMNI6malG+4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788970422; c=relaxed/simple; bh=VUTBmdEVnBswjD7t6pKHutus3keF7X0UwAfTRGWdWLU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=UE+/MGZlatAhXBa0iG2nBZyiKR+cv1swnkglbXMs2YGijgh766gJ167YIF1l01skG1Dd+gxXBYz7BZdvumLOrl06IzRNjz7k1qYzTmn7Ye6AxUt4acs3nG3JdqXaCbVct6aTXXMROL8V9S2cz2Lf/x2IicdjRRcOubEpQ69Czno= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Kqv4EsDC; 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="Kqv4EsDC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 753C11F00A3A; Wed, 9 Sep 2026 16:13:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788970421; bh=xkt3XXg0SwTU3EJO6CTYWHJMMsarbm/Q69gMMQQ1MUM=; h=From:To:Cc:Subject:Date:Reply-To; b=Kqv4EsDCR9RxaKr3B8WLVfmzy00ChVapc00gJhlEMaOkmverqbq8zIqd2YO1xGGXx lbUh+VC2Xg0hUolvDY5tOLq7uFdsUFjze3k4WaM6CbV5FsewxA+zt52rJlXY+NkvWh pr8Ss4UGhtsIA/B/+//aB1Fk44kNNlvXIugYm2rw= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-80920: io_uring: defer eventfd signaling when queued from a wakeup handler Date: Wed, 9 Sep 2026 18:13:20 +0200 Message-ID: <2026090915-CVE-2026-80920-9c6d@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=3065; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=joOLHPTyQCT10q8A5P+E6No7JM5+q9mXdlq7/Q8wpU8=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkLW2c/44hrT5oXEOLxt2pRsVT50/K9T45NiHhkMHWpl M6EuEcOHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjARzQ0Ms5hmOmxf9C98l9Yh PeZt8semJzuc0mOYK1U0UWr10W+f979hUZ8n8KvufOUebwA= 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: io_uring: defer eventfd signaling when queued from a wakeup handler io_req_local_work_add() signals the CQ ring eventfd inline when it is the one to push the first entry onto ->work_list. For DEFER_TASKRUN rings that add is frequently done from a waitqueue wakeup handler, where an arbitrary waitqueue lock is held. eventfd_signal_mask() only refuses to recurse when current->in_eventfd is set, but that bit is set by eventfd_signal_mask() itself. If the wake chain starts somewhere else, signal goes out inline and can feed back into epoll. Add IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three waitqueue callbacks, and use it to force io_eventfd_signal() down the existing call_rcu_hurry() deferral instead of signaling inline. The Linux kernel CVE team has assigned CVE-2026-80920 to this issue. Affected and fixed versions =========================== Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 6.18.49 with commit e22f4494cc9487d326e5e3067f33dea7c1e442b2 Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 7.1.11 with commit b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 7.2.1 with commit 40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 7.3-rc1 with commit cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e 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-2026-80920 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: include/linux/io_uring_types.h io_uring/eventfd.c io_uring/eventfd.h io_uring/futex.c io_uring/io_uring.c io_uring/poll.c io_uring/tw.c io_uring/waitid.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/e22f4494cc9487d326e5e3067f33dea7c1e442b2 https://git.kernel.org/stable/c/b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f https://git.kernel.org/stable/c/40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a https://git.kernel.org/stable/c/cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e