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

Vulnerability 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.

References

• https://git.kernel.org/stable/c/c8d179f3b1c1d60bf4484f50aa67b4c70f91bff9
• https://git.kernel.org/stable/c/246428bfb9e7db15c5cd08e1d0eca41b65af2b06
• https://git.kernel.org/stable/c/0f78f09466744589e420935e646ae78212a38290
• https://git.kernel.org/stable/c/4059507e34aa5fe0fa9fd5b2b5f0c8b26ab2d482
• https://git.kernel.org/stable/c/dc9d0e3cfd16f66fbf0862857c6b391c8613ca9f
• https://git.kernel.org/stable/c/c87f1f6ade56c711f8736901e330685b453e420e
• https://git.kernel.org/stable/c/9fc17b76fc70763780aa78b38fcf4742384044a5