netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.15.200, 6.1.163, 4.20, 5.5, 5.11, and 4 more
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate() nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required. nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones. Compare the non-catchall activate callback, which is correct: nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive */ With the buggy catchall version: nft_map_catchall_activate(): if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */ The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use-after-free. This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES. Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From 25aa2ad37c2162be1c0bc4fe6397f7e4c13f00f8 · fixed in 8c760ba4e36c750379d13569f23f5a6e185333f5; From d60be2da67d172aecf866302c91ea11533eca4d9 · fixed in b9b6573421de51829f7ec1cce76d85f5f6fbbd7f; From 628bd3e49cba1c066228e23d71a852c23e26da73 · fixed in 42c574c1504aa089a0a142e4c13859327570473d; From 628bd3e49cba1c066228e23d71a852c23e26da73 · fixed in 1444ff890b4653add12f734ffeffc173d42862dd; From 628bd3e49cba1c066228e23d71a852c23e26da73 · fixed in 8b68a45f9722f2babe9e7bad00aa74638addf081; From 628bd3e49cba1c066228e23d71a852c23e26da73 · fixed in f41c5d151078c5348271ffaf8e7410d96f2d82f8; From 5.15.121 · fixed in 5.15.200; From 6.1.36 · fixed in 6.1.163; From 4.19.316 · fixed in 4.20; From 5.4.262 · fixed in 5.5; From 5.10.188 · fixed in 5.11; From 6.3.10 · fixed in 6.4
- Linux Linux
6.4
- KernelLinux
fixed in 5.15.200; From 5.16.0 · fixed in 6.1.163; From 6.2.0 · fixed in 6.6.124; From 6.4.0 · fixed in 6.12.70; From 6.7.0 · fixed in 6.18.10