CVE-2026-90146 (GCVE-0-2026-90146)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:06 – Updated: 2026-09-18 17:53
VLAI
Title
bpf, xdp: move offload check into dev_xdp_install()
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf, xdp: move offload check into dev_xdp_install() bpf_xdp_link_update() calls dev_xdp_install() directly and skips dev_xdp_attach(), so the checks in dev_xdp_attach() do not run. A user can make an XDP link with a normal program and then swap in an offloaded or device-bound program with BPF_LINK_UPDATE, which puts it on the software path. dev_xdp_install() is the one place all three paths go through: "ip link set xdp" and BPF_LINK_CREATE reach it via dev_xdp_attach(), and BPF_LINK_UPDATE calls it directly. So move the program checks (offloaded, bound to another device, device-bound in generic mode, native vs generic, DEVMAP and CPUMAP) there, and keep only the netlink-flag check (XDP_FLAGS_UPDATE_IF_NOEXIST) in dev_xdp_attach().
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 026a4c28e1db3b0cb99cd9a3e495d4a8b632fa74 , < ea7b35dcc9430293b861bc7bad0c546f193c85f9 (git)
Affected: 026a4c28e1db3b0cb99cd9a3e495d4a8b632fa74 , < 03022dd874070768a7099f18b1944c633641315f (git)
Affected: 026a4c28e1db3b0cb99cd9a3e495d4a8b632fa74 , < ad27ed7d2309419a129078d781504f486b1b469a (git)
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Linux Linux Affected: 5.9
Unaffected: 0 , < 5.9 (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, xdp: move offload check into dev_xdp_install()\n\nbpf_xdp_link_update() calls dev_xdp_install() directly and skips\ndev_xdp_attach(), so the checks in dev_xdp_attach() do not run. A user can\nmake an XDP link with a normal program and then swap in an offloaded or\ndevice-bound program with BPF_LINK_UPDATE, which puts it on the software\npath.\n\ndev_xdp_install() is the one place all three paths go through:\n\"ip link set xdp\" and BPF_LINK_CREATE reach it via dev_xdp_attach(), and\nBPF_LINK_UPDATE calls it directly. So move the program checks (offloaded,\nbound to another device, device-bound in generic mode, native vs generic,\nDEVMAP and CPUMAP) there, and keep only the netlink-flag check\n(XDP_FLAGS_UPDATE_IF_NOEXIST) in dev_xdp_attach()."
        }
      ],
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            "baseSeverity": "HIGH",
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            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The attacker-controlled data is the replacement program fd on bpf(BPF_LINK_UPDATE), which __sys_bpf() dispatches to link_update() then bpf_xdp_link_update() in net/core/dev.c; that local syscall installs the prog, rather than a parsed ksmbd/nfsd/packet payload.\nAC:L - bpf_xdp_link_update() only compares prog-\u003etype and expected_attach_type, so BPF_LINK_CREATE of a normal XDP prog on a veth with XDP_FLAGS_SKB_MODE followed by BPF_LINK_UPDATE of a BPF_F_XDP_DEV_BOUND_ONLY prog that calls bpf_xdp_metadata_rx_* always bypasses the skipped dev_xdp_attach() checks, with no race.\nPR:L - bpf_prog_load() of BPF_PROG_TYPE_XDP requires bpf_token_capable(CAP_BPF) and bpf_token_capable(CAP_NET_ADMIN) before bpf_xdp_link_attach()/link_update(); those caps, and the CAP_NET_ADMIN to add the veth attach target, are obtainable in a user/netns via unshare and BPF token delegation, not only init-namespace root.\nUI:N - The attacker loads both programs, creates the XDP link, calls BPF_LINK_UPDATE, and then drives do_xdp_generic() by sending a frame through their own veth peer; no victim mount, file open, or other cooperative action is required.\nS:U - The confused metadata kfuncs (veth_xdp_rx_hash() and friends) run in the host kernel XDP path do_xdp_generic()/bpf_prog_run_generic_xdp() and corrupt host kernel memory; this is not a KVM/Xen guest-to-host escape or an IOMMU/DMA boundary bypass.\nC:H - After the skipped bpf_prog_is_dev_bound() checks, a veth-bound program can run on generic XDP\u0027s stack struct xdp_buff; veth_xdp_rx_timestamp()/veth_xdp_rx_vlan_tag() cast it to veth_xdp_buff and read skb_hwtstamps()/vlan fields through that bogus skb pointer, an unbounded kernel read into BPF maps.\nI:H - The same confused veth_xdp_buff.skb is passed to skb_get_hash(), which writes hash/sw_hash/l4_hash via __skb_get_hash_net(); swapping a veth-bound prog onto mlx5 native XDP likewise treats mlx5e_xdp_buff.cqe as an sk_buff and writes into the CQE, which is type confusion with a kernel write.\nA:H - do_xdp_generic() allocates a bare struct xdp_buff, so the next RX after the bad BPF_LINK_UPDATE makes veth_xdp_rx_hash() or mlx5e_xdp_rx_timestamp() dereference adjacent stack/wrapper bytes as skb, cqe, or rq and oops; an offloaded prog swapped onto the software path also hits bpf_prog_warn_on_exec() per packet."
            }
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    "datePublished": "2026-09-17T16:06:41.695Z",
    "dateReserved": "2026-09-11T19:38:34.789Z",
    "dateUpdated": "2026-09-18T17:53:23.835Z",
    "state": "PUBLISHED"
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, xdp: move offload check into dev_xdp_install()\n\nbpf_xdp_link_update() calls dev_xdp_install() directly and skips\ndev_xdp_attach(), so the checks in dev_xdp_attach() do not run. A user can\nmake an XDP link with a normal program and then swap in an offloaded or\ndevice-bound program with BPF_LINK_UPDATE, which puts it on the software\npath.\n\ndev_xdp_install() is the one place all three paths go through:\n\"ip link set xdp\" and BPF_LINK_CREATE reach it via dev_xdp_attach(), and\nBPF_LINK_UPDATE calls it directly. So move the program checks (offloaded,\nbound to another device, device-bound in generic mode, native vs generic,\nDEVMAP and CPUMAP) there, and keep only the netlink-flag check\n(XDP_FLAGS_UPDATE_IF_NOEXIST) in dev_xdp_attach()."
          }
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        "lastModified": "2026-09-18T18:17:43.987",
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        "vulnStatus": "Received"
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    }
  }
}



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