{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-27020", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-27020" ], "published": "2024-05-01T05:31:05Z", "summary": "netfilter: nf_tables: Fix potential data-race in __nft_expr_type_get()", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: Fix potential data-race in __nft_expr_type_get()\n\nnft_unregister_expr() can concurrent with __nft_expr_type_get(),\nand there is not any protection when iterate over nf_tables_expressions\nlist in __nft_expr_type_get(). Therefore, there is potential data-race\nof nf_tables_expressions list entry.\n\nUse list_for_each_entry_rcu() to iterate over nf_tables_expressions\nlist in __nft_expr_type_get(), and use rcu_read_lock() in the caller\nnft_expr_type_get() to protect the entire type query process.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2", "1:6.1.58-1+rpt2", "1:6.1.63-1+rpt1", "1:6.1.73-1+rpt1", "1:6.6.20-1+rpt1", "1:6.6.28-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": 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"6f16847710cc0502450788b9f12f0a14d3429668", "upstream_version": "6.6.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.6.29" }, "1:6.6.28-1+rpt1": { "linux_commit": "0c341f47adc3578cd5f817aa20ee2b7f9ae6b23e", "upstream_version": "6.6.28", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.6.29" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2024-27020" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/939109c0a8e2a006a6cc8209e262d25065f4403a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b38a133d37fa421c8447b383d788c9cc6f5cb34c" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/934e66e231cff2b18faa2c8aad0b8cec13957e05" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/0b6de00206adbbfc6373b3ae38d2a6f197987907" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8d56bad42ac4c43c6c72ddd6a654a2628bf839c5" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a9ebf340d123ae12582210407f879d6a5a1bc25b" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/01f1a678b05ade4b1248019c2dcca773aebbeb7f" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/f969eb84ce482331a991079ab7a5c4dc3b7f89bf" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:52:36Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The vulnerable path is reached only through NETLINK_NETFILTER messages (NFT_MSG_NEWRULE/NEWSET batches) sent by a local process on the same host. Per kernel scoring guidance, netfilter/nftables netlink configuration is a local attack vector.\nAC:L - The attacker fully controls the reader side (unbounded NFT_MSG_NEWRULE batches in one netns) and can drive the writer side by forcing expression-module autoload from a second netns, where nf_tables_module_autoload() intentionally releases commit_mutex before request_module(); because the writer holds only the global nfnl mutex and the reader only the per-netns commit_mutex, the two run concurrently with no shared lock and the race can be retried indefinitely.\nPR:L - nfnetlink gates on netlink_net_capable(skb, CAP_NET_ADMIN), which resolves to ns_capable() against the network namespace's owning user namespace, so an ordinary unprivileged user obtains it with \"unshare -Urn\". No real root or init-namespace capability is needed.\nUI:N - The attacker performs the entire sequence \u2014 creating namespaces, issuing nftables batches, and triggering module autoload \u2014 with no action by any other user or administrator.\nS:U - The race and its consequences are confined to the kernel of the same host; there is no crossing into a different security authority such as a hypervisor or IOMMU boundary.\nC:H - Losing the RCU protection lets nft_expr_type_get() retain a pointer into module memory past free_module()'s synchronize_rcu(), so type->owner, type->name, type->maxattr and type->policy are read from freed and potentially reclaimed memory; an attacker-controlled reclaim of that module-region allocation combined with the attacker-supplied nla_policy parse yields kernel memory disclosure.\nI:H - try_module_get() performs an atomic increment through a dangling type->owner pointer, giving a write into freed memory, and type->select_ops/type->ops become indirect calls through freed module-region storage that can be reclaimed (e.g. by another module load or BPF JIT allocation), making control-flow hijack achievable.\nA:H - Dereferencing the stale nft_expr_type and the freed struct module after the module's vmalloc'd memory is released causes an oops or panic, and the unsynchronized traversal of a concurrently modified list can itself derail into invalid pointers." } } }