Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: do not account for OoO in mptcp_rcvbuf_grow() MPTCP-level OoOs are physiological when multiple subflows are active concurrently and will not cause retransmissions nor are caused by drops. Accounting for them in mptcp_rcvbuf_grow() causes the rcvbuf slowly drifting towards tcp_rmem[2]. Remove such accounting. Note that subflows will still account for TCP-level OoO when the MPTCP-level rcvbuf is propagated. This also closes a subtle and very unlikely race condition with rcvspace init; active sockets with user-space holding the msk-level socket lock, could complete such initialization in the receive callback, after that the first OoO data reaches the rcvbuf and potentially triggering a divide by zero Oops.

References 3

• git.kernel.org https://git.kernel.org/stable/c/400ee4854adef1e4983812a3decf6717ea020136
• git.kernel.org https://git.kernel.org/stable/c/6b329393502e5857662b851a13f947209c588587
• git.kernel.org https://git.kernel.org/stable/c/fb7bf00b04a6b48859f52035d4e745848c2b4c79

Remediation