GHSA-4969-9GF7-VMR2
Vulnerability from github – Published: 2026-08-05 09:31 – Updated: 2026-08-05 09:31In the Linux kernel, the following vulnerability has been resolved:
xfrm: policy: preallocate inexact bins before xfrm_hash_rebuild reinsert
xfrm_hash_rebuild()'s first loop preallocates the bins/chains the reinsert loop needs, so the reinsert (after hlist_del_rcu()) cannot allocate or fail. But its guard is inverted: it skips policies with prefixlen < threshold and preallocates for the rest.
prefixlen < threshold is exactly when policy_hash_bysel() returns NULL and the reinsert takes the allocating xfrm_policy_inexact_insert() path. So the loop preallocates for the exact policies (which never allocate) and skips the inexact ones, whose bin/node is then allocated GFP_ATOMIC during reinsert. On failure the error path only WARN_ONCE()s and continues, leaving a poisoned bydst node; the next rebuild's hlist_del_rcu() dereferences LIST_POISON2 and takes a GPF. Reachable under memory pressure, deterministic via failslab.
Invert the guard so preallocation covers exactly the reinserted policies; the reinsert then allocates nothing and cannot fail.
Crash: Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI KASAN: maybe wild-memory-access in range [0xdead...] ... Workqueue: events xfrm_hash_rebuild RIP: 0010:xfrm_hash_rebuild+0x5b3/0x1190 RAX: dead000000000122 (LIST_POISON2 + offset) ... Call Trace: hlist_del_rcu (include/linux/rculist.h:599) xfrm_hash_rebuild (net/xfrm/xfrm_policy.c:1365) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) ret_from_fork_asm (arch/x86/entry/entry_64.S:245) ... Kernel panic - not syncing: Fatal exception in interrupt
{
"affected": [],
"aliases": [
"CVE-2026-64579"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-05T08:16:37Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: policy: preallocate inexact bins before xfrm_hash_rebuild reinsert\n\nxfrm_hash_rebuild()\u0027s first loop preallocates the bins/chains the reinsert\nloop needs, so the reinsert (after hlist_del_rcu()) cannot allocate or\nfail. But its guard is inverted: it skips policies with prefixlen \u003c\nthreshold and preallocates for the rest.\n\nprefixlen \u003c threshold is exactly when policy_hash_bysel() returns NULL and\nthe reinsert takes the allocating xfrm_policy_inexact_insert() path. So the\nloop preallocates for the exact policies (which never allocate) and skips\nthe inexact ones, whose bin/node is then allocated GFP_ATOMIC during\nreinsert. On failure the error path only WARN_ONCE()s and continues,\nleaving a poisoned bydst node; the next rebuild\u0027s hlist_del_rcu()\ndereferences LIST_POISON2 and takes a GPF. Reachable under memory pressure,\ndeterministic via failslab.\n\nInvert the guard so preallocation covers exactly the reinserted policies;\nthe reinsert then allocates nothing and cannot fail.\n\nCrash:\n Oops: general protection fault, probably for non-canonical address\n 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI\n KASAN: maybe wild-memory-access in range [0xdead...]\n ...\n Workqueue: events xfrm_hash_rebuild\n RIP: 0010:xfrm_hash_rebuild+0x5b3/0x1190\n RAX: dead000000000122 (LIST_POISON2 + offset)\n ...\n Call Trace:\n hlist_del_rcu (include/linux/rculist.h:599)\n xfrm_hash_rebuild (net/xfrm/xfrm_policy.c:1365)\n process_one_work (kernel/workqueue.c:3322)\n worker_thread (kernel/workqueue.c:3486)\n kthread (kernel/kthread.c:436)\n ret_from_fork (arch/x86/kernel/process.c:158)\n ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n ...\n Kernel panic - not syncing: Fatal exception in interrupt",
"id": "GHSA-4969-9gf7-vmr2",
"modified": "2026-08-05T09:31:17Z",
"published": "2026-08-05T09:31:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64579"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6aa3796d18a9fda953ad76a62b57bf6c145cb9ef"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7acc5ed2f33608a3d83b64f50a5766843b6e2485"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/94c00391a5117530188334f740ce26d3f1256190"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d9d9cc21cc90014724a14c447e3d587be9447107"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f38f8cce2f7e79775b3db7e8a5eacda04ac908e4"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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