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 781B145DF41 for ; Sun, 18 Oct 2026 16:25:02 +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=1792340703; cv=none; b=OYQTThHDS7l+wHiJzDVD4z4DcJzfANGtm/jCFRUrWYsHk8nodEmEME8+Rjp9Ll69E31XiQZsJLWzzYiffxssTTm9VC9QzJJIsu2YbHmyc0LjAWZnmw1k6qGD3Fphf9UD1ojhTnACDVKTq7EOvIHX9sPHjX8zco2ZKIdsTPUunk8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792340703; c=relaxed/simple; bh=8k32kC3l3xwI73vnsaLmPwfG+o6ASBJwmKUlStd+YGE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=SFqZYIs6eBL9Isn+RUE4tjxrTxu6x6SarUXcA839gbdSzvgHaU0z8NkA662vkKjtYDeGnqimzgoRLxfkVizRU1nW9rW3jYwTuON9rjsZIjiCZtEfDGgaaLbFPeDWnlXcW86f05N6z8BfYW1Lc5b65zbd8CTCfufUZ/XPwHnEWUw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2Fm/Ql1g; 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="2Fm/Ql1g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B4251F000C4; Sun, 18 Oct 2026 16:25:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792340702; bh=+h82B7lahumE20qPZ19Up6yVVDlzZxrwqq5KIzpdZPc=; h=From:To:Cc:Subject:Date:Reply-To; b=2Fm/Ql1g9CWtgUA4IRqTyANddhDbRTaw7j4DUH5xHS19X3X7cu7Scypz1LtoEVkkc BsBSKsds4CF/Qhjuu1J2/M4Bxcs8ACb5m7dzkIs2aNmwfJQvmsBRZJKvHyV7Q0qzbk JdcK4FFkiiCUrGUT8MHqClHM+wG0euPwtXc7uZEw= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-98809: Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister Date: Sun, 18 Oct 2026 17:46:24 +0200 Message-ID: <2026101826-CVE-2026-98809-086a@gregkh> X-Mailer: git-send-email 2.56.0 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=3551; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=6IqTPEVLvj8+6ce2MT20gyzx/cIBt/YMnkq1uxv8AVM=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlXXkZpmJ7nv/n03K8TF5YdUhdpE57dKMyv3mT97YlEe p7jXX6mjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjI3DsM82sf+/rkf3kocMdi 9fGcTfPqp5/W+c8wP/P3qbrbEU6dh43UTUv0b156fVJVAQA= 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: Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister hci_unregister_dev() disables cmd_work and cmd_timer, then calls hci_cmd_sync_clear(), whose cancel_work_sync() waits for hci_cmd_sync_work() to return. That worker dequeues and runs every entry on cmd_sync_work_list. With cmd_work disabled nothing reaches the controller, so each queued HCI command waits the full HCI_CMD_TIMEOUT (2s). The backlog has no bound. Userspace can keep queuing MGMT commands such as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't answer. Closing /dev/vhci then blocks in vhci_release() for backlog * 2s: INFO: task syz-executor:5749 blocked for more than 143 seconds. cancel_work_sync hci_cmd_sync_clear hci_unregister_dev vhci_release In a local reproduction the backlog held more than 5000 entries, which comes to hours of hang. Stop the worker from taking new entries once HCI_UNREGISTER is set, and wake any request still waiting with -ENODEV before cancelling the work. The entries left over are destroyed with -ECANCELED by the existing sweep in hci_cmd_sync_clear(). They stay on the list until the work has stopped, so hci_cmd_sync_dequeue() and friends still see them. A callback already running may still issue another command, which delays unregister by at most one timeout per remaining command, not by the whole backlog. The Linux kernel CVE team has assigned CVE-2026-98809 to this issue. Affected and fixed versions =========================== Issue introduced in 5.17 with commit 008ee9eb8a11bcabf12c91771dd4f470b082bd44 and fixed in 6.12.113 with commit 143bde97c4101ae68eb656c87e620c45b07a3090 Issue introduced in 5.17 with commit 008ee9eb8a11bcabf12c91771dd4f470b082bd44 and fixed in 6.18.56 with commit 7f16443a30f4e86d84ae4faf057d333b41ddb757 Issue introduced in 5.17 with commit 008ee9eb8a11bcabf12c91771dd4f470b082bd44 and fixed in 7.2.10 with commit e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c Issue introduced in 5.17 with commit 008ee9eb8a11bcabf12c91771dd4f470b082bd44 and fixed in 7.3-rc6 with commit b1f24c1ab52345e810c42a1a81286cb5a7c92252 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-2026-98809 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: net/bluetooth/hci_sync.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/143bde97c4101ae68eb656c87e620c45b07a3090 https://git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757 https://git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c https://git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252