CVE-2025-21639 Information

Description

In the Linux kernel the following vulnerability has been resolved:

sctp: sysctl: rto_min/max: avoid using current->nsproxy

As mentioned in a previous commit of this series using the ’net' structure via ‘current’ is not recommended for different reasons:

• Inconsistency: getting info from the reader’s/writer’s netns vs only from the opener’s netns.

• current->nsproxy can be NULL in some cases resulting in an ‘Oops’ (null-ptr-deref) e.g. when the current task is exiting as spotted by syzbot [1] using acct(2).

The ’net’ structure can be obtained from the table->data using container_of().

Note that table->data could also be used directly as this is the only member needed from the ’net’ structure but that would increase the size of this fix to use ‘data’ everywhere ’net->sctp.rto_min/max’ is used.

Reference

https://git.kernel.org/stable/c/4059507e34aa5fe0fa9fd5b2b5f0c8b26ab2d482 https://git.kernel.org/stable/c/9fc17b76fc70763780aa78b38fcf4742384044a5 https://git.kernel.org/stable/c/c87f1f6ade56c711f8736901e330685b453e420e https://git.kernel.org/stable/c/dc9d0e3cfd16f66fbf0862857c6b391c8613ca9f