Description

In the Linux kernel, the following vulnerability has been resolved: ublk: fix use-after-free in ublk_partition_scan_work A race condition exists between the async partition scan work and device teardown that can lead to a use-after-free of ub->ub_disk: 1. ublk_ctrl_start_dev() schedules partition_scan_work after add_disk() 2. ublk_stop_dev() calls ublk_stop_dev_unlocked() which does: - del_gendisk(ub->ub_disk) - ublk_detach_disk() sets ub->ub_disk = NULL - put_disk() which may free the disk 3. The worker ublk_partition_scan_work() then dereferences ub->ub_disk leading to UAF Fix this by using ublk_get_disk()/ublk_put_disk() in the worker to hold a reference to the disk during the partition scan. The spinlock in ublk_get_disk() synchronizes with ublk_detach_disk() ensuring the worker either gets a valid reference or sees NULL and exits early. Also change flush_work() to cancel_work_sync() to avoid running the partition scan work unnecessarily when the disk is already detached.

Weaknesses 1

Affected Products 2

References 2

• git.kernel.org https://git.kernel.org/stable/c/72e28774e9644c2bdbb4920842fbf77103a15a85
  Patch
• git.kernel.org https://git.kernel.org/stable/c/f0d385f6689f37a2828c686fb279121df006b4cb
  Patch

Remediation

• git.kernel.org https://git.kernel.org/stable/c/72e28774e9644c2bdbb4920842fbf77103a15a85
  Patch
• git.kernel.org https://git.kernel.org/stable/c/f0d385f6689f37a2828c686fb279121df006b4cb
  Patch