Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix refcount leak on table dump There is a reference count leak in ctnetlink_dump_table(): if (res < 0) { nf_conntrack_get(&ct->ct_general); // HERE cb->args[1] = (unsigned long)ct; ... While its very unlikely, its possible that ct == last. If this happens, then the refcount of ct was already incremented. This 2nd increment is never undone. This prevents the conntrack object from being released, which in turn keeps prevents cnet->count from dropping back to 0. This will then block the netns dismantle (or conntrack rmmod) as nf_conntrack_cleanup_net_list() will wait forever. This can be reproduced by running conntrack_resize.sh selftest in a loop. It takes ~20 minutes for me on a preemptible kernel on average before I see a runaway kworker spinning in nf_conntrack_cleanup_net_list. One fix would to change this to: if (res < 0) { if (ct != last) nf_conntrack_get(&ct->ct_general); But this reference counting isn't needed in the first place. We can just store a cookie value instead. A followup patch will do the same for ctnetlink_exp_dump_table, it looks to me as if this has the same problem and like ctnetlink_dump_table, we only need a 'skip hint', not the actual object so we can apply the same cookie strategy there as well.
Product status
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before 586892e341fbf698e7cbaca293e1353957db725a
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before 962518c6ca9f9a13df099cafa429f72f68ad61f0
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before 19b909a4b1452fb97e477d2f08b97f8d04095619
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before 41462f4cfc583513833f87f9ee55d12da651a7e3
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before 30cf811058552b8cd0e98dff677ef3f89d6d34ce
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before a2cb4df7872de069f809de2f076ec8e54d649fe3
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before e14f72aa66c029db106921d621edcedef68e065b
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b
d205dc40798d97d63ad348bfaf7394f445d152d4 (git) before de788b2e6227462b6dcd0e07474e72c089008f74
2.6.18
Any version before 2.6.18
5.4.297 (semver)
5.10.241 (semver)
5.15.190 (semver)
6.1.149 (semver)
6.6.103 (semver)
6.12.43 (semver)
6.15.11 (semver)
6.16.2 (semver)
6.17 (original_commit_for_fix)
References
git.kernel.org/...c/586892e341fbf698e7cbaca293e1353957db725a
git.kernel.org/...c/962518c6ca9f9a13df099cafa429f72f68ad61f0
git.kernel.org/...c/19b909a4b1452fb97e477d2f08b97f8d04095619
git.kernel.org/...c/41462f4cfc583513833f87f9ee55d12da651a7e3
git.kernel.org/...c/30cf811058552b8cd0e98dff677ef3f89d6d34ce
git.kernel.org/...c/a2cb4df7872de069f809de2f076ec8e54d649fe3
git.kernel.org/...c/e14f72aa66c029db106921d621edcedef68e065b
git.kernel.org/...c/a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b
git.kernel.org/...c/de788b2e6227462b6dcd0e07474e72c089008f74
