Описание
In the Linux kernel, the following vulnerability has been resolved:
xfrm: state: fix out-of-bounds read during lookup
lookup and resize can run in parallel.
The xfrm_state_hash_generation seqlock ensures a retry, but the hash
functions can observe a hmask value that is too large for the new hlist
array.
rehash does:
rcu_assign_pointer(net->xfrm.state_bydst, ndst) [..]
net->xfrm.state_hmask = nhashmask;
While state lookup does:
h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family);
hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h, bydst) {
This is only safe in case the update to state_bydst is larger than
net->xfrm.xfrm_state_hmask (or if the lookup function gets
serialized via state spinlock again).
Fix this by prefetching state_hmask and the associated pointers.
The xfrm_state_hash_generation seqlock retry will ensure that the pointer
and the hmask will be consistent.
The existing helpers, like xfrm_dst_hash(), are now unsafe for RCU side,
add lockdep assertions to document that they are only safe for insert
side.
xfrm_state_lookup_byaddr() uses the spinlock rather than RCU.
AFAICS this is an oversight from back when state lookup was converted to
RCU, this lock should be replaced with RCU in a future patch.
A flaw was found in the Linux kernel. This vulnerability allows a local user to cause a Denial of Service (DoS) via a system crash. A race condition between table resizing and state lookup operations in the IPsec packet transformation (xfrm) subsystem can cause the kernel to perform an out-of-bounds memory read during concurrent state lookups.
Отчет
This vulnerability is rated as Moderate impact because exploiting the race condition requires precise timing during IPsec state table resizing, with the primary blast radius limited to a denial of service via a kernel crash rather than arbitrary code execution. In Red Hat Enterprise Linux environments, the xfrm framework is utilized when IPsec packet transformation or tunneling services are active, and modifying state tables generally requires administrative networking privileges. Systems that do not actively manage or process IPsec traffic are unlikely to encounter the concurrent table modification conditions necessary to trigger this flaw.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Out of support scope | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 10 | kernel | Fixed | RHSA-2025:20095 | 11.11.2025 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2025:20518 | 11.11.2025 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2025:20518 | 11.11.2025 |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: xfrm: state: fix out-of-bounds read during lookup lookup and resize can run in parallel. The xfrm_state_hash_generation seqlock ensures a retry, but the hash functions can observe a hmask value that is too large for the new hlist array. rehash does: rcu_assign_pointer(net->xfrm.state_bydst, ndst) [..] net->xfrm.state_hmask = nhashmask; While state lookup does: h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family); hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h, bydst) { This is only safe in case the update to state_bydst is larger than net->xfrm.xfrm_state_hmask (or if the lookup function gets serialized via state spinlock again). Fix this by prefetching state_hmask and the associated pointers. The xfrm_state_hash_generation seqlock retry will ensure that the pointer and the hmask will be consistent. The existing helpers, like xfrm_dst_hash(), are now unsafe for RCU side, add lockdep assertions to d...
In the Linux kernel, the following vulnerability has been resolved: xfrm: state: fix out-of-bounds read during lookup lookup and resize can run in parallel. The xfrm_state_hash_generation seqlock ensures a retry, but the hash functions can observe a hmask value that is too large for the new hlist array. rehash does: rcu_assign_pointer(net->xfrm.state_bydst, ndst) [..] net->xfrm.state_hmask = nhashmask; While state lookup does: h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family); hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h, bydst) { This is only safe in case the update to state_bydst is larger than net->xfrm.xfrm_state_hmask (or if the lookup function gets serialized via state spinlock again). Fix this by prefetching state_hmask and the associated pointers. The xfrm_state_hash_generation seqlock retry will ensure that the pointer and the hmask will be consistent. The existing helpers, like xfrm_dst_hash(), are now unsafe for RCU side, add lockdep as
In the Linux kernel, the following vulnerability has been resolved: x ...
In the Linux kernel, the following vulnerability has been resolved: xfrm: state: fix out-of-bounds read during lookup lookup and resize can run in parallel. The xfrm_state_hash_generation seqlock ensures a retry, but the hash functions can observe a hmask value that is too large for the new hlist array. rehash does: rcu_assign_pointer(net->xfrm.state_bydst, ndst) [..] net->xfrm.state_hmask = nhashmask; While state lookup does: h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family); hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h, bydst) { This is only safe in case the update to state_bydst is larger than net->xfrm.xfrm_state_hmask (or if the lookup function gets serialized via state spinlock again). Fix this by prefetching state_hmask and the associated pointers. The xfrm_state_hash_generation seqlock retry will ensure that the pointer and the hmask will be consistent. The existing helpers, like xfrm_dst_hash(), are now unsafe for RCU side, add lockdep...
EPSS
5.5 Medium
CVSS3