Linux Kernel up to 6.8.6 pds_core pci_reset_function deadlock

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.8.6. The impacted element is the function pci_reset_function of the component pds_core. The manipulation results in deadlock. This vulnerability is reported as CVE-2024-35968. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.8.6. It has been classified as critical. Affected is the function pci_reset_function of the component pds_core. The manipulation with an unknown input leads to a deadlock vulnerability. CWE is classifying the issue as CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: pds_core: Fix pdsc_check_pci_health function to use work thread When the driver notices fw_status == 0xff it tries to perform a PCI reset on itself via pci_reset_function() in the context of the driver's health thread. However, pdsc_reset_prepare calls pdsc_stop_health_thread(), which attempts to stop/flush the health thread. This results in a deadlock because the stop/flush will never complete since the driver called pci_reset_function() from the health thread context. Fix by changing the pdsc_check_pci_health_function() to queue a newly introduced pdsc_pci_reset_thread() on the pdsc's work queue. Unloading the driver in the fw_down/dead state uncovered another issue, which can be seen in the following trace: WARNING: CPU: 51 PID: 6914 at kernel/workqueue.c:1450 __queue_work+0x358/0x440 [...] RIP: 0010:__queue_work+0x358/0x440 [...] Call Trace: ? __warn+0x85/0x140 ? __queue_work+0x358/0x440 ? report_bug+0xfc/0x1e0 ? handle_bug+0x3f/0x70 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? __queue_work+0x358/0x440 queue_work_on+0x28/0x30 pdsc_devcmd_locked+0x96/0xe0 [pds_core] pdsc_devcmd_reset+0x71/0xb0 [pds_core] pdsc_teardown+0x51/0xe0 [pds_core] pdsc_remove+0x106/0x200 [pds_core] pci_device_remove+0x37/0xc0 device_release_driver_internal+0xae/0x140 driver_detach+0x48/0x90 bus_remove_driver+0x6d/0xf0 pci_unregister_driver+0x2e/0xa0 pdsc_cleanup_module+0x10/0x780 [pds_core] __x64_sys_delete_module+0x142/0x2b0 ? syscall_trace_enter.isra.18+0x126/0x1a0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7fbd9d03a14b [...] Fix this by preventing the devcmd reset if the FW is not running.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2024-35968 since 05/17/2024. The exploitability is told to be difficult. There are known technical details, but no exploit is available.

Upgrading to version 6.8.7 eliminates this vulnerability. Applying the patch 38407914d482/81665adf25d2 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.8.0
• 6.8.1
• 6.8.2
• 6.8.3
• 6.8.4
• 6.8.5
• 6.8.6

License

• open-source

Website

• Vendor: https://www.kernel.org/

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