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.
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.
Metrics
Affected Vendors & Products
Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 15 Aug 2026 12:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | ublk: reset kernel-owned dev_info fields in ublk_ctrl_add_dev() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
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Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T12:27:08.759Z
Reserved: 2026-08-15T05:44:03.902Z
Link: CVE-2026-74472
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.