GHSA-W4CH-7P82-3M56
Vulnerability from github – Published: 2026-01-23 18:31 – Updated: 2026-07-14 15:31In the Linux kernel, the following vulnerability has been resolved:
net: fix memory leak in skb_segment_list for GRO packets
When skb_segment_list() is called during packet forwarding, it handles packets that were aggregated by the GRO engine.
Historically, the segmentation logic in skb_segment_list assumes that individual segments are split from a parent SKB and may need to carry their own socket memory accounting. Accordingly, the code transfers truesize from the parent to the newly created segments.
Prior to commit ed4cccef64c1 ("gro: fix ownership transfer"), this truesize subtraction in skb_segment_list() was valid because fragments still carry a reference to the original socket.
However, commit ed4cccef64c1 ("gro: fix ownership transfer") changed this behavior by ensuring that fraglist entries are explicitly orphaned (skb->sk = NULL) to prevent illegal orphaning later in the stack. This change meant that the entire socket memory charge remained with the head SKB, but the corresponding accounting logic in skb_segment_list() was never updated.
As a result, the current code unconditionally adds each fragment's truesize to delta_truesize and subtracts it from the parent SKB. Since the fragments are no longer charged to the socket, this subtraction results in an effective under-count of memory when the head is freed. This causes sk_wmem_alloc to remain non-zero, preventing socket destruction and leading to a persistent memory leak.
The leak can be observed via KMEMLEAK when tearing down the networking environment:
unreferenced object 0xffff8881e6eb9100 (size 2048): comm "ping", pid 6720, jiffies 4295492526 backtrace: kmem_cache_alloc_noprof+0x5c6/0x800 sk_prot_alloc+0x5b/0x220 sk_alloc+0x35/0xa00 inet6_create.part.0+0x303/0x10d0 __sock_create+0x248/0x640 __sys_socket+0x11b/0x1d0
Since skb_segment_list() is exclusively used for SKB_GSO_FRAGLIST packets constructed by GRO, the truesize adjustment is removed.
The call to skb_release_head_state() must be preserved. As documented in commit cf673ed0e057 ("net: fix fraglist segmentation reference count leak"), it is still required to correctly drop references to SKB extensions that may be overwritten during __copy_skb_header().
{
"affected": [],
"aliases": [
"CVE-2026-22979"
],
"database_specific": {
"cwe_ids": [
"CWE-401"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-23T16:15:53Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: fix memory leak in skb_segment_list for GRO packets\n\nWhen skb_segment_list() is called during packet forwarding, it handles\npackets that were aggregated by the GRO engine.\n\nHistorically, the segmentation logic in skb_segment_list assumes that\nindividual segments are split from a parent SKB and may need to carry\ntheir own socket memory accounting. Accordingly, the code transfers\ntruesize from the parent to the newly created segments.\n\nPrior to commit ed4cccef64c1 (\"gro: fix ownership transfer\"), this\ntruesize subtraction in skb_segment_list() was valid because fragments\nstill carry a reference to the original socket.\n\nHowever, commit ed4cccef64c1 (\"gro: fix ownership transfer\") changed\nthis behavior by ensuring that fraglist entries are explicitly\norphaned (skb-\u003esk = NULL) to prevent illegal orphaning later in the\nstack. This change meant that the entire socket memory charge remained\nwith the head SKB, but the corresponding accounting logic in\nskb_segment_list() was never updated.\n\nAs a result, the current code unconditionally adds each fragment\u0027s\ntruesize to delta_truesize and subtracts it from the parent SKB. Since\nthe fragments are no longer charged to the socket, this subtraction\nresults in an effective under-count of memory when the head is freed.\nThis causes sk_wmem_alloc to remain non-zero, preventing socket\ndestruction and leading to a persistent memory leak.\n\nThe leak can be observed via KMEMLEAK when tearing down the networking\nenvironment:\n\nunreferenced object 0xffff8881e6eb9100 (size 2048):\n comm \"ping\", pid 6720, jiffies 4295492526\n backtrace:\n kmem_cache_alloc_noprof+0x5c6/0x800\n sk_prot_alloc+0x5b/0x220\n sk_alloc+0x35/0xa00\n inet6_create.part.0+0x303/0x10d0\n __sock_create+0x248/0x640\n __sys_socket+0x11b/0x1d0\n\nSince skb_segment_list() is exclusively used for SKB_GSO_FRAGLIST\npackets constructed by GRO, the truesize adjustment is removed.\n\nThe call to skb_release_head_state() must be preserved. As documented in\ncommit cf673ed0e057 (\"net: fix fraglist segmentation reference count\nleak\"), it is still required to correctly drop references to SKB\nextensions that may be overwritten during __copy_skb_header().",
"id": "GHSA-w4ch-7p82-3m56",
"modified": "2026-07-14T15:31:32Z",
"published": "2026-01-23T18:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-22979"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0b27828ebd1ed3107d7929c3737adbe862e99e74"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/238e03d0466239410b72294b79494e43d4fabe77"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3264881431e308b9c72cb8a0159d57a56d67dd79"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/88bea149db2057112af3aaf63534b24fab5858ab"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c114a32a2e70b82d447f409f7ffcfa3058f9d5bd"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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