Description
In the Linux kernel, the following vulnerability has been resolved: virtio: fix use-after-free in unregister_virtio_device() device_unregister() is device_del() plus put_device(). When the caller holds no extra reference, that drops the last one and runs the release callback, which for several transports frees the memory the embedded struct virtio_device sits in. unregister_virtio_device() then calls virtio_debug_device_exit(), which reads dev->debugfs_dir out of the freed object. Affected transports are the ones whose release callback frees and whose remove path takes no reference: virtio_mmio, virtio_vdpa, virtio_uml, mlxbf-tmfifo and virtio_ccw. virtio_pci is unaffected because virtio_pci_remove() brackets the call with get_device() and put_device(). Remove the debugfs entries before the device can go away. They are only accessed through the protected debugfs interface, so debugfs_remove_recursive() waits for in-progress file operations before returning. Tearing them down while the device is still alive is therefore safe. Reproduced on User-Mode Linux with CONFIG_KASAN and CONFIG_VIRTIO_DEBUG by unbinding a virtio-uml device: BUG: KASAN: slab-use-after-free in virtio_debug_device_exit+0x36/0x4d Read of size 8 at addr 00000000616e0b10 by task init/1 __asan_report_load8_noabort virtio_debug_device_exit+0x36/0x4d unregister_virtio_device+0x48/0x75 virtio_uml_remove platform_remove device_release_driver_internal unbind_store Freed by task 1: kfree virtio_uml_release_dev device_release kobject_put put_device device_unregister With this applied, the report is gone and unbind is clean.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
96a8326d69fffd7e8c2eb737dc060d8009a33b39 to < 951cad50cba89e736afdee4a730e0e52f9245c9baffected96a8326d69fffd7e8c2eb737dc060d8009a33b39 to < 77dbd10a701a30fdfea5c3bb7a29163128f9a9c7affected96a8326d69fffd7e8c2eb737dc060d8009a33b39 to < caf042153016d651b55d0fb4a63cdf7d0d23dee2affected96a8326d69fffd7e8c2eb737dc060d8009a33b39 to < 3f9a0fceb730f5107d52421ead5568eae25a0049affected
Linux Linux
Default version status: affected
6.10affected0 to < 6.10unaffected6.12.111 to ≤ 6.12.*unaffected6.18.53 to ≤ 6.18.*unaffected7.2.7 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected