RDMA/rxe: Fix incomplete state save in rxe_requester

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix incomplete state save in rxe_requester If a send packet is dropped by the IP layer in rxe_requester() the call to rxe_xmit_packet() can fail with err == -EAGAIN. To recover, the state of the wqe is restored to the state before the packet was sent so it can be resent. However, the routines that save and restore the state miss a significnt part of the variable state in the wqe, the dma struct which is used to process through the sge table. And, the state is not saved before the packet is built which modifies the dma struct. Under heavy stress testing with many QPs on a fast node sending large messages to a slow node dropped packets are observed and the resent packets are corrupted because the dma struct was not restored. This patch fixes this behavior and allows the test cases to succeed.

References

• https://git.kernel.org/stable/c/70518f3aaf5a059b691867d7d2d46b999319656a
• https://git.kernel.org/stable/c/2f2a6422287fe29f9343247d77b645100ece0652
• https://git.kernel.org/stable/c/255c0e60e1d16874fc151358d94bc8df661600dd
• https://git.kernel.org/stable/c/5d122db2ff80cd2aed4dcd630befb56b51ddf947