CVE-2025-21641

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 readers/writers netns vs only from the openers 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().