| 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-2024-53194: PCI: Fix use-after-free of slot->bus on hot remove |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| PCI: Fix use-after-free of slot->bus on hot remove |
| |
| Dennis reports a boot crash on recent Lenovo laptops with a USB4 dock. |
| |
| Since commit 0fc70886569c ("thunderbolt: Reset USB4 v2 host router") and |
| commit 59a54c5f3dbd ("thunderbolt: Reset topology created by the boot |
| firmware"), USB4 v2 and v1 Host Routers are reset on probe of the |
| thunderbolt driver. |
| |
| The reset clears the Presence Detect State and Data Link Layer Link Active |
| bits at the USB4 Host Router's Root Port and thus causes hot removal of the |
| dock. |
| |
| The crash occurs when pciehp is unbound from one of the dock's Downstream |
| Ports: pciehp creates a pci_slot on bind and destroys it on unbind. The |
| pci_slot contains a pointer to the pci_bus below the Downstream Port, but |
| a reference on that pci_bus is never acquired. The pci_bus is destroyed |
| before the pci_slot, so a use-after-free ensues when pci_slot_release() |
| accesses slot->bus. |
| |
| In principle this should not happen because pci_stop_bus_device() unbinds |
| pciehp (and therefore destroys the pci_slot) before the pci_bus is |
| destroyed by pci_remove_bus_device(). |
| |
| However the stacktrace provided by Dennis shows that pciehp is unbound from |
| pci_remove_bus_device() instead of pci_stop_bus_device(). To understand |
| the significance of this, one needs to know that the PCI core uses a two |
| step process to remove a portion of the hierarchy: It first unbinds all |
| drivers in the sub-hierarchy in pci_stop_bus_device() and then actually |
| removes the devices in pci_remove_bus_device(). There is no precaution to |
| prevent driver binding in-between pci_stop_bus_device() and |
| pci_remove_bus_device(). |
| |
| In Dennis' case, it seems removal of the hierarchy by pciehp races with |
| driver binding by pci_bus_add_devices(). pciehp is bound to the |
| Downstream Port after pci_stop_bus_device() has run, so it is unbound by |
| pci_remove_bus_device() instead of pci_stop_bus_device(). Because the |
| pci_bus has already been destroyed at that point, accesses to it result in |
| a use-after-free. |
| |
| One might conclude that driver binding needs to be prevented after |
| pci_stop_bus_device() has run. However it seems risky that pci_slot points |
| to pci_bus without holding a reference. Solely relying on correct ordering |
| of driver unbind versus pci_bus destruction is certainly not defensive |
| programming. |
| |
| If pci_slot has a need to access data in pci_bus, it ought to acquire a |
| reference. Amend pci_create_slot() accordingly. Dennis reports that the |
| crash is not reproducible with this change. |
| |
| Abridged stacktrace: |
| |
| pcieport 0000:00:07.0: PME: Signaling with IRQ 156 |
| pcieport 0000:00:07.0: pciehp: Slot #12 AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug+ Surprise+ Interlock- NoCompl+ IbPresDis- LLActRep+ |
| pci_bus 0000:20: dev 00, created physical slot 12 |
| pcieport 0000:00:07.0: pciehp: Slot(12): Card not present |
| ... |
| pcieport 0000:21:02.0: pciehp: pcie_disable_notification: SLOTCTRL d8 write cmd 0 |
| Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI |
| CPU: 13 UID: 0 PID: 134 Comm: irq/156-pciehp Not tainted 6.11.0-devel+ #1 |
| RIP: 0010:dev_driver_string+0x12/0x40 |
| pci_destroy_slot |
| pciehp_remove |
| pcie_port_remove_service |
| device_release_driver_internal |
| bus_remove_device |
| device_del |
| device_unregister |
| remove_iter |
| device_for_each_child |
| pcie_portdrv_remove |
| pci_device_remove |
| device_release_driver_internal |
| bus_remove_device |
| device_del |
| pci_remove_bus_device (recursive invocation) |
| pci_remove_bus_device |
| pciehp_unconfigure_device |
| pciehp_disable_slot |
| pciehp_handle_presence_or_link_change |
| pciehp_ist |
| |
| The Linux kernel CVE team has assigned CVE-2024-53194 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 4.19.325 with commit 50473dd3b2a08601a078f852ea05572de9b1f86c |
| Fixed in 5.4.287 with commit d0ddd2c92b75a19a37c887154223372b600fed37 |
| Fixed in 5.10.231 with commit da6e6ff1f6c57f16e07af955e0e997fc90dd1e75 |
| Fixed in 5.15.174 with commit 41bbb1eb996be1435815aa1fbcc9ffc45b84cc12 |
| Fixed in 6.1.120 with commit 20502f0b3f3acd6bee300257556c27a867f80c8b |
| Fixed in 6.6.64 with commit e5d5c04aac71bf1476dc44b56f2206a4c2facca8 |
| Fixed in 6.11.11 with commit c8266ab8e7ccd1d1f5a9c8b29eb2020175048134 |
| Fixed in 6.12.2 with commit 69d2ceac11acf8579d58d55c9c5b65fb658f916e |
| Fixed in 6.13 with commit c7acef99642b763ba585f4a43af999fcdbcc3dc4 |
| |
| 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-2024-53194 |
| 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/pci/slot.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/50473dd3b2a08601a078f852ea05572de9b1f86c |
| https://git.kernel.org/stable/c/d0ddd2c92b75a19a37c887154223372b600fed37 |
| https://git.kernel.org/stable/c/da6e6ff1f6c57f16e07af955e0e997fc90dd1e75 |
| https://git.kernel.org/stable/c/41bbb1eb996be1435815aa1fbcc9ffc45b84cc12 |
| https://git.kernel.org/stable/c/20502f0b3f3acd6bee300257556c27a867f80c8b |
| https://git.kernel.org/stable/c/e5d5c04aac71bf1476dc44b56f2206a4c2facca8 |
| https://git.kernel.org/stable/c/c8266ab8e7ccd1d1f5a9c8b29eb2020175048134 |
| https://git.kernel.org/stable/c/69d2ceac11acf8579d58d55c9c5b65fb658f916e |
| https://git.kernel.org/stable/c/c7acef99642b763ba585f4a43af999fcdbcc3dc4 |
