CVE-2026-64579 is a vulnerability in Linux Kernel
Published on August 5, 2026
xfrm: policy: preallocate inexact bins before xfrm_hash_rebuild reinsert
In 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
Products Associated with CVE-2026-64579
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Affected Versions
Linux:- Version 24969facd704a5f0dd8e08da86bf32a9ce972bee and below d9d9cc21cc90014724a14c447e3d587be9447107 is affected.
- Version 24969facd704a5f0dd8e08da86bf32a9ce972bee and below 94c00391a5117530188334f740ce26d3f1256190 is affected.
- Version 24969facd704a5f0dd8e08da86bf32a9ce972bee and below 7acc5ed2f33608a3d83b64f50a5766843b6e2485 is affected.
- Version 24969facd704a5f0dd8e08da86bf32a9ce972bee and below 6aa3796d18a9fda953ad76a62b57bf6c145cb9ef is affected.
- Version 24969facd704a5f0dd8e08da86bf32a9ce972bee and below f38f8cce2f7e79775b3db7e8a5eacda04ac908e4 is affected.
- Version 5.0 is affected.
- Before 5.0 is unaffected.
- Version 6.6.148, <= 6.6.* is unaffected.
- Version 6.12.101, <= 6.12.* is unaffected.
- Version 6.18.42, <= 6.18.* is unaffected.
- Version 7.1.6, <= 7.1.* is unaffected.
- Version 7.2-rc4, <= * is unaffected.