CVE Catalog

CVE-2021-47001

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Elevated risk
0.74%

51th percentile - higher than 51% of all known CVEs

Summary

In the Linux kernel's xprtrdma (RPC-over-RDMA), after a reconnect, the reply handler opens the congestion window (cwnd) before enough Receive WRs are posted, causing an RNR error and immediate connection loss.

Risk Assessment

Instability of NFS/RDMA connections, leading to data access interruptions.

Recommendation

Apply a kernel patch that reorders cwnd update relative to post_recvs.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: xprtrdma: Fix cwnd update ordering After a reconnect, the reply handler is opening the cwnd (and thus enabling more RPC Calls to be sent) /before/ rpcrdma_post_recvs() can post enough Receive WRs to receive their replies. This causes an RNR and the new connection is lost immediately. The race is most clearly exposed when KASAN and disconnect injection are enabled. This slows down rpcrdma_rep_create() enough to allow the send side to post a bunch of RPC Calls before the Receive completion handler can invoke ib_post_recv().

Vulnerability data from NVD (NIST) · CISA KEV · EPSS