CVE-2026-74472

Summary

In the Linux kernel, the following vulnerability has been resolved:

ublk: reset kernel-owned dev_info fields in ublk_ctrl_add_dev()

ublk_ctrl_add_dev() memcpy()s the userspace ublksrv_ctrl_dev_info into ub->dev_info and then fixes up the fields the driver owns, but misses ->state and ->ublksrv_pid.

A device added with ->state = UBLK_S_DEV_LIVE passes the "->state != UBLK_S_DEV_DEAD" test that ublk_stop_dev_unlocked() uses as its proxy for "a disk is attached", while ->ub_disk is still NULL, so DEL_DEV right after ADD_DEV oopses in del_gendisk(). UBLK_S_DEV_QUIESCED plus UBLK_F_USER_RECOVERY dies one step earlier, in ublk_force_abort_dev(). A poisoned ->state also gets START_USER_RECOVERY and the char device read/write path onto a device that was never started, and wedges START_DEV at -EEXIST. A poisoned ->ublksrv_pid just makes GET_DEV_INFO report an unrelated task as the ublk server.

Reset both after the memcpy(), as ublk_detach_disk() does. Userspace only ever reads these back, so correcting them silently breaks nothing.

ADD_DEV has copied ->state in unsanitized since ublk was merged, but back then it was harmless: the gendisk was allocated during ADD_DEV, and both teardown and the START_DEV -EEXIST check keyed off disk_live() rather than ->state. The oops became reachable once the disk allocation moved to START_DEV and those checks switched to ->state.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/ee41b00858ca65b4428e99efe39a4277c1f043d2
• https://git.kernel.org/stable/c/b67ce16b26ad0f14cfd6071013840aa95f823bea
• https://git.kernel.org/stable/c/205feb72e5beb3140e4e1403b6cff30cf739bab9
• https://git.kernel.org/stable/c/127033b79383a3e78361d7e971588aa8849f5124
• https://git.kernel.org/stable/c/e65848e4ce352bac9e3465099354c8b8f845391f

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