CVE-2026-64474vfio: prevent infinite loop in vfio_mig_get_next_state() on blocked arc

Official description

In the Linux kernel, the following vulnerability has been resolved: vfio: prevent infinite loop in vfio_mig_get_next_state() on blocked arc vfio_mig_get_next_state() walks vfio_from_fsm_table[] one step at a time, looping to skip optional states the device does not support until *next_fsm is supported. A blocked transition is encoded as VFIO_DEVICE_STATE_ERROR, which the trailing return reports as -EINVAL. The skip loop does not account for the ERROR sentinel. state_flags_table[ERROR] is ~0U and vfio_from_fsm_table[ERROR][*] is ERROR, so once *next_fsm becomes ERROR the loop condition stays true and *next_fsm never changes. The blocked arcs STOP_COPY -> PRE_COPY and STOP_COPY -> PRE_COPY_P2P map to ERROR yet pass the support check on a precopy-capable device, causing the loop to spin forever while holding the driver state mutex. This can result in a soft lockup, and a panic with softlockup_panic set. Terminate the skip loop on the ERROR sentinel so a blocked transition falls through to the existing return and reports -EINVAL.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/8e872c07e40d51a66dee7b280a23a460a2e1e3fa
• https://git.kernel.org/stable/c/ed7d5599e6c398da74845767cd1e6a8370a160fc
• https://git.kernel.org/stable/c/7f2d6b31089e48db4653df832c9a6afdde9a1c29
• https://git.kernel.org/stable/c/a3a8afa2f6e7f0dc266d08f02be3f3054241ba47
• https://git.kernel.org/stable/c/a26b499b757cfc8bbff1088bb1b844639e250893