CVE-2025-21641 Information

Description

In the Linux kernel the following vulnerability has been resolved:

mptcp: sysctl: blackhole timeout: avoid using current->nsproxy

As mentioned in the previous commit 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 ‘pernet’ structure can be obtained from the table->data using container_of().

Reference

https://git.kernel.org/stable/c/4c74fbdc5ab95b13945be01e6065940b68222db7 https://git.kernel.org/stable/c/92cf7a51bdae24a32c592adcdd59a773ae149289