CVE-2021-47010
Description
In the Linux kernel, the following vulnerability has been resolved: net: Only allow init netns to set default tcp cong to a restricted algo tcp_set_default_congestion_control() is netns-safe in that it writes to &net->ipv4.tcp_congestion_control, but it also sets ca->flags |= TCP_CONG_NON_RESTRICTED which is not namespaced. This has the unintended side-effect of changing the global net.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it is read-only: 97684f0970f6 ("net: Make tcp_allowed_congestion_control readonly in non-init netns") Resolve this netns "leak" by only allowing the init netns to set the default algorithm to one that is restricted. This restriction could be removed if tcp_allowed_congestion_control were namespace-ified in the future. This bug was uncovered with https://github.com/JonathonReinhart/linux-netns-sysctl-verify
How to fix
- linux linux_kernel4.19.191, 5.4.119, 5.10.37, 5.11.21, 5.12.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| linux linux_kernel | 4.15 ≤ v < 4.19.191, 4.20 ≤ v < 5.4.119, 5.5 ≤ v < 5.10.37, 5.11 ≤ v < 5.11.21, 5.12 ≤ v < 5.12.4 | 4.19.191, 5.4.119, 5.10.37, 5.11.21, 5.12.4 |
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