GHSA-JW2Q-X793-GP2M
Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-06 09:31In the Linux kernel, the following vulnerability has been resolved:
esp: downgrade zerocopy managed frags before mutating skb frags
On the out-of-place output path (esp->inplace == false) ESP rewrites the skb frag array: esp_output_head() appends a trailer frag and esp_output_tail() replaces the frags with a destination page, both referenced with get_page().
When the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the payload frags are owned by the ubuf and must not be referenced or unreferenced individually, but ESP mutates the frag array without ever downgrading the skb. This breaks the managed-frag invariant two ways:
-
esp_ssg_unref() walks the source scatterlist and drops a page reference for every frag, including the ubuf-owned payload frags, pushing their refcount below the GUP pin bias while the pages are still pinned, i.e. a use-after-free of the zerocopy pages;
-
esp_output_tail() installs its destination page as frag 0 with get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so skb_release_data() takes the skip_unref branch and never drops that reference, leaking the x->xfrag page at packet rate.
Fix this the way every other frag-mutating site does (__ip_append_data(), __ip6_append_data(), tcp_sendmsg_locked()) and call skb_zcopy_downgrade_managed() before ESP touches the frag array: it takes a real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS, so the per-frag unref in esp_ssg_unref() and the frag release in skb_release_data() are both balanced and no mixed-ownership frag array is left behind.
{
"affected": [],
"aliases": [
"CVE-2026-98368"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-06T09:18:31Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp-\u003einplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb. This breaks the managed-frag invariant two ways:\n\n - esp_ssg_unref() walks the source scatterlist and drops a page\n reference for every frag, including the ubuf-owned payload frags,\n pushing their refcount below the GUP pin bias while the pages are\n still pinned, i.e. a use-after-free of the zerocopy pages;\n\n - esp_output_tail() installs its destination page as frag 0 with\n get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n skb_release_data() takes the skip_unref branch and never drops that\n reference, leaking the x-\u003exfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind.",
"id": "GHSA-jw2q-x793-gp2m",
"modified": "2026-10-06T09:31:36Z",
"published": "2026-10-06T09:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98368"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"
}
],
"schema_version": "1.4.0",
"severity": []
}
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