Vulnerability CVE-2021-47001
Published: 2024-02-28

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().

 References:
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
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