CVE-2025-21637

Description

In the Linux kernel, the following vulnerability has been resolved: sctp: sysctl: udp_port: 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 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 net structure can be obtained from the table->data using container_of(). Note that table->data could also be used directly, but that would increase the size of this fix, while sctp.ctl_sock still needs to be retrieved from net structure.