2.0 KiB
CVE-2024-50217
Description
In the Linux kernel, the following vulnerability has been resolved:btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()Mounting btrfs from two images (which have the same one fsid and twodifferent dev_uuids) in certain executing order may trigger an UAF forvariable 'device->bdev_file' in __btrfs_free_extra_devids(). Andfollowing are the details:1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs devices by ioctl(BTRFS_IOC_SCAN_DEV): / btrfs_device_1 → loop0 fs_device \ btrfs_device_2 → loop12. mount /dev/loop0 /mnt btrfs_open_devices btrfs_device_1->bdev_file = btrfs_get_bdev_and_sb(loop0) btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1) btrfs_fill_super open_ctree fail: btrfs_close_devices // -ENOMEM btrfs_close_bdev(btrfs_device_1) fput(btrfs_device_1->bdev_file) // btrfs_device_1->bdev_file is freed btrfs_close_bdev(btrfs_device_2) fput(btrfs_device_2->bdev_file)3. mount /dev/loop1 /mnt btrfs_open_devices btrfs_get_bdev_and_sb(&bdev_file) // EIO, btrfs_device_1->bdev_file is not assigned, // which points to a freed memory area btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1) btrfs_fill_super open_ctree btrfs_free_extra_devids if (btrfs_device_1->bdev_file) fput(btrfs_device_1->bdev_file) // UAF !Fix it by setting 'device->bdev_file' as 'NULL' after closing thebtrfs_device in btrfs_close_one_device().
POC
Reference
No PoCs from references.