net: openvswitch: conntrack: fix helper UAF due to extensions realloc

Summary

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: conntrack: fix helper UAF due to extensions realloc While calling the helpers, a raw pointer to the extensions area is wired into expectations list: -> nf_ct_helper() -> helper->help() -> nf_ct_expect_related_report() -> nf_ct_expect_insert() -> hlist_add_head_rcu(&exp->lnode, &master_help->expectations) In case the connection is not confirmed yet, more extensions can be added afterwards with *_ext_add() calls reallocating the extension space and leaving the now invalid pointer in the expectations list that is later accessed while removing the expectation. Make sure that helpers are called at the end after all the other extensions are already added. Note that the helper rejection now leaves the mark and labels set, but that's not different from how the NAT was handled before or how the mark and the labels were handled on confirmation failure. And there are no atomicity guarantees provided by the API anyway.

Affected versions

• Linux Linux

  From cae3a2627520c3795b54533c5328b77af3405dbe · fixed in 18866dc1f525f9ee4de7709529d1ae1af8d8e8be; From cae3a2627520c3795b54533c5328b77af3405dbe · fixed in afcf362625190c5260530b1d6c7daa98831f6b83; From cae3a2627520c3795b54533c5328b77af3405dbe · fixed in 5f23080a625dd7855ab91485c8d691a54a1979f0; From cae3a2627520c3795b54533c5328b77af3405dbe · fixed in e02a83bb0b7a203f6a22f55ad5f426765560f811; From cae3a2627520c3795b54533c5328b77af3405dbe · fixed in 1a4151e6be57b098b7a5ebfbde58585e83200cdc

• Linux Linux

  4.3

• KernelLinux

  From 4.3.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.112; From 6.13.0 · fixed in 6.18.55; From 6.19.0 · fixed in 7.2.9

References 5