CVE-2021-47614

What it actually does

Use-after-free in the RDMA/irdma driver when irdma_hmc_sd_one fails: the 'chunk' structure is freed while still linked on the PBLE info list because the list insertion occurs before the SD operation succeeds.

Why it matters to the business

Kernel memory corruption risk on systems running the affected RDMA code, potentially causing crashes or limited code execution; low observed exploitation probability and no ransomware usage reduce immediate operational disruption.

How an attack unfolds

An attacker triggers the failure path inside add_pble_prm by forcing irdma_hmc_sd_one to fail, leaving a dangling reference to the already-freed chunk that can be abused for memory reuse attacks.

How to fix it

Apply the upstream fix by updating fluid-cloudnative/fluid to commit e0184cff8790ad000c3e8943392c7f544fad7d66 or later; ensure the corresponding Linux kernel irdma driver receives the same ordering change for PBLE list insertion.

How to confirm the fix worked

Confirm the presence of the corrected ordering (list insertion after successful irdma_hmc_sd_one) in the running kernel source or verify the exact commit hash in the fluid repository; recompile and test the RDMA module under failure injection for irdma_hmc_sd_one.

Typical attack path

1. Reach RDMA/irdma code path that calls add_pble_prm
2. Force irdma_hmc_sd_one to return failure
3. Reuse the freed chunk memory before the list is cleaned
4. Corrupt kernel structures to achieve code execution or denial of service

How to detect it

Search kernel logs and crash dumps for irdma_hmc_sd_one failure paths followed by unexpected PBLE list references; examine auditd or system call traces around RDMA allocation routines for anomalous chunk reuse.

What your security team should do

• Prioritize patching systems that load the irdma driver within the next maintenance window
• Monitor EPSS and KEV updates for any future increase in exploit maturity
• Audit RDMA-enabled hosts for the vulnerable commit and schedule kernel upgrades
• Review downstream dependents of fluid-cloudnative/fluid for inherited exposure