| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-26620: s390/vfio-ap: always filter entire AP matrix |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| s390/vfio-ap: always filter entire AP matrix |
| |
| The vfio_ap_mdev_filter_matrix function is called whenever a new adapter or |
| domain is assigned to the mdev. The purpose of the function is to update |
| the guest's AP configuration by filtering the matrix of adapters and |
| domains assigned to the mdev. When an adapter or domain is assigned, only |
| the APQNs associated with the APID of the new adapter or APQI of the new |
| domain are inspected. If an APQN does not reference a queue device bound to |
| the vfio_ap device driver, then it's APID will be filtered from the mdev's |
| matrix when updating the guest's AP configuration. |
| |
| Inspecting only the APID of the new adapter or APQI of the new domain will |
| result in passing AP queues through to a guest that are not bound to the |
| vfio_ap device driver under certain circumstances. Consider the following: |
| |
| guest's AP configuration (all also assigned to the mdev's matrix): |
| 14.0004 |
| 14.0005 |
| 14.0006 |
| 16.0004 |
| 16.0005 |
| 16.0006 |
| |
| unassign domain 4 |
| unbind queue 16.0005 |
| assign domain 4 |
| |
| When domain 4 is re-assigned, since only domain 4 will be inspected, the |
| APQNs that will be examined will be: |
| 14.0004 |
| 16.0004 |
| |
| Since both of those APQNs reference queue devices that are bound to the |
| vfio_ap device driver, nothing will get filtered from the mdev's matrix |
| when updating the guest's AP configuration. Consequently, queue 16.0005 |
| will get passed through despite not being bound to the driver. This |
| violates the linux device model requirement that a guest shall only be |
| given access to devices bound to the device driver facilitating their |
| pass-through. |
| |
| To resolve this problem, every adapter and domain assigned to the mdev will |
| be inspected when filtering the mdev's matrix. |
| |
| The Linux kernel CVE team has assigned CVE-2024-26620 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.0 with commit 48cae940c31d2407d860d87c41d5f9871c0521db and fixed in 6.1.76 with commit d6b8d034b576f406af920a7bee81606c027b24c6 |
| Issue introduced in 6.0 with commit 48cae940c31d2407d860d87c41d5f9871c0521db and fixed in 6.6.15 with commit c69d821197611678533fb3eb784fc823b921349a |
| Issue introduced in 6.0 with commit 48cae940c31d2407d860d87c41d5f9871c0521db and fixed in 6.7.3 with commit cdd134d56138302976685e6c7bc4755450b3880e |
| Issue introduced in 6.0 with commit 48cae940c31d2407d860d87c41d5f9871c0521db and fixed in 6.8 with commit 850fb7fa8c684a4c6bf0e4b6978f4ddcc5d43d11 |
| |
| 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-2024-26620 |
| 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: |
| drivers/s390/crypto/vfio_ap_ops.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/d6b8d034b576f406af920a7bee81606c027b24c6 |
| https://git.kernel.org/stable/c/c69d821197611678533fb3eb784fc823b921349a |
| https://git.kernel.org/stable/c/cdd134d56138302976685e6c7bc4755450b3880e |
| https://git.kernel.org/stable/c/850fb7fa8c684a4c6bf0e4b6978f4ddcc5d43d11 |
