Entreprise française de cybersécurité depuis 2004
☎ 03 60 47 09 81 - info@securiteinfo.com
☎ 03 60 47 09 81 - info@securiteinfo.com
In the Linux kernel, the following vulnerability has been resolved:btrfs: qgroup: fix race between quota disable and quota rescan ioctlThere's a race between a task disabling quotas and another running therescan ioctl that can result in a use-after-free of qgroup records fromthe fs_info->qgroup_tree rbtree.This happens as follows:1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan();2) Task B enters btrfs_quota_disable() and calls btrfs_qgroup_wait_for_completion(), which does nothing because at that point fs_info->qgroup_rescan_running is false (it wasn't set yet by task A);3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock;4) Task A enters qgroup_rescan_zero_tracking() which starts iterating the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock, but task B is freeing qgroup records from that tree without holding the lock, resulting in a use-after-free.Fix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config().Also at btrfs_qgroup_rescan() don't start the rescan worker if quotaswere already disabled.
No PoCs from references.
- https://github.com/w4zu/Debian_security