CVE-2021-47001 Information

Description

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().

Reference

https://git.kernel.org/stable/c/eddae8be7944096419c2ae29477a45f767d0fcd4 https://git.kernel.org/stable/c/8834ecb5df22b7ff3c9b0deba7726579bb613f95 https://git.kernel.org/stable/c/19b5fa9489b5706bc878c3a522a7f771079e2fa0 https://git.kernel.org/stable/c/35d8b10a25884050bb3b0149b62c3818ec59f77c