net: reject oversized tx_queue_len at netlink parse time
Summary
| CVE | CVE-2026-98021 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-09-25 11:17:30 UTC |
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| Updated | 2026-09-25 11:17:30 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
net: reject oversized tx_queue_len at netlink parse time
rtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len
without going through netif_change_tx_queue_len(), so a device created
with "ip link add ... txqueuelen 500000" bypasses the S16_MAX cap and
still triggers the oversized ring allocations in pfifo_fast, tun and
tap. The veth peer nest (rtnl_nla_parse_ifinfomsg()) and the
RTM_NEWLINK-on-existing-device path reach the same sinks.
Enforce the cap in ifla_policy instead: IFLA_TXQLEN becomes
NLA_POLICY_FULL_RANGE(NLA_U32, &txqlen_range) with
txqlen_range = { .min = 0, .max = S16_MAX }. All netlink consumers
parse against this policy - rtnl_setlink(), rtnl_newlink() (create
and change), and the veth peer nest - so every netlink path is capped
at parse time and rejects the attribute with -ERANGE plus a proper
"integer out of range" extack message before any device state is
modified (the RTM_SETLINK half-application wart is gone with it).
Document the bound in the rt-link.yaml netlink spec.
Conditions to recreate the bug:
- CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y.
- Unprivileged user in a fresh user+net namespace (unshare -Urn):
ip link add v0 txqueuelen 500000 type veth peer name v1
-> on the fixed kernel this is rejected with -ERANGE ("integer out
of range" extack) instead of installing an oversized tx_queue_len
that later inflates pfifo_fast/tun/tap ring allocations.
- ip link set v0 txqueuelen 500000 is likewise rejected at parse time. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 45ca9f59b6c7ea70e0a17054902b8a556913db34 git |
Not specified |
| CNA |
Linux |
Linux |
affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 2fd0880f0272ec022906a05587fd91416ebecc38 git |
Not specified |
| CNA |
Linux |
Linux |
affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 a638a2625aa83160a394abe8e8b2e524a80c771b git |
Not specified |
| CNA |
Linux |
Linux |
affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 1aa9e143bf51405665a793d4cc925e1c4f0c5922 git |
Not specified |
| CNA |
Linux |
Linux |
affected 2.6.23 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 2.6.23 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.111 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.53 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.7 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3-rc3 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.