nvmet: copy the hostid into the ctrl before creating PR pc_refs

Summary

In the Linux kernel, the following vulnerability has been resolved: nvmet: copy the hostid into the ctrl before creating PR pc_refs Commit 6202783184bf ("nvmet: Improve nvmet_alloc_ctrl() interface and implementation") added a second uuid_copy() of args->hostid near the end of nvmet_alloc_ctrl(), and commit 7b658153f1b8 ("nvmet: Remove duplicate uuid_copy") removed the original copy that sat before nvmet_ctrl_init_pr() instead of the new one. Since then nvmet_ctrl_init_pr() snapshots ctrl->hostid into the per-controller per-namespace reservation refs while the uuid_copy() from the connect data runs later, after the controller is published. The ctrl is allocated with kzalloc(), so every pc_ref created on this path stores the nil UUID. pc_ref->hostid has a single consumer: nvmet_pr_set_ctrl_to_abort() matches it against the preempted registrant's hostid to kill and drain the victim's in-flight I/O for Preempt and Abort. The match can never hit with the nil UUID, so whenever a namespace with reservations enabled exists before a host connects, which includes every reconnect, Preempt and Abort silently degrades into a plain Preempt: the preempting host sees success while the victim's in-flight I/O is still in the air. Copy the hostid where the rest of the connect data is consumed, before the controller is published and before nvmet_ctrl_init_pr() takes its snapshot.

Timeline

1. Oct 18, 2026, 3:46 PM UTCCVE published
2. Oct 19, 2026, 9:24 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 7b658153f1b8a79ed98980f2fef7b92a66aeb9cd · fixed in d3d6d7efdacc08616d23b3ac42272a494951dc0f; From 7b658153f1b8a79ed98980f2fef7b92a66aeb9cd · fixed in 23194531595c5d1d4454e3a607b0c8fc0c4e8695; From 7b658153f1b8a79ed98980f2fef7b92a66aeb9cd · fixed in 5211fed41d7ec90e9ab7239dc4bffffe4d0b2b62

• Linux Linux

  6.15

• KernelLinux

  From 6.15.0 · fixed in 6.18.56; From 6.19.0 · fixed in 7.2.10

References 3