CVE-2023-52925

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: don't fail inserts if duplicate has expired

nftables selftests fail: run-tests.sh testcases/sets/0044intervaloverlap0 Expected: 0-2 . 0-3, got: W: [FAILED] ./testcases/sets/0044intervaloverlap0: got 1

Insertion must ignore duplicate but expired entries.

Moreover, there is a strange asymmetry in nftpipapoactivate:

It refetches the current element, whereas the other ->activate callbacks (bitmap, hash, rhash, rbtree) use elem->priv. Same for .remove: other set implementations take elem->priv, nftpipaporemove fetches elem->priv, then does a relookup, remove this.

I suspect this was the reason for the change that prompted the removal of the expired check in pipapo_get() in the first place, but skipping exired elements there makes no sense to me, this helper is used for normal get requests, insertions (duplicate check) and deactivate callback.

In first two cases expired elements must be skipped.

For ->deactivate(), this gets called for DELSETELEM, so it seems to me that expired elements should be skipped as well, i.e. delete request should fail with -ENOENT error.