CVE-2021-47010

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: Only allow init netns to set default tcp cong to a restricted algo<br /> <br /> tcp_set_default_congestion_control() is netns-safe in that it writes<br /> to &amp;net-&gt;ipv4.tcp_congestion_control, but it also sets<br /> ca-&gt;flags |= TCP_CONG_NON_RESTRICTED which is not namespaced.<br /> This has the unintended side-effect of changing the global<br /> net.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it<br /> is read-only: 97684f0970f6 ("net: Make tcp_allowed_congestion_control<br /> readonly in non-init netns")<br /> <br /> Resolve this netns "leak" by only allowing the init netns to set the<br /> default algorithm to one that is restricted. This restriction could be<br /> removed if tcp_allowed_congestion_control were namespace-ified in the<br /> future.<br /> <br /> This bug was uncovered with<br /> https://github.com/JonathonReinhart/linux-netns-sysctl-verify