net/sched: Abort __tc_modify_qdisc if parent class does not exist
In the Linux kernel, the following vulnerability has been resolved: net/sched: Abort __tc_modify_qdisc if parent class does not exist Lion's patch [1] revealed an ancient bug in the qdisc API. Whenever a user creates/modifies a qdisc specifying as a parent another qdisc, the qdisc API will, during grafting, detect that the user is not trying to attach to a class and reject. However grafting is performed after qdisc_create (and thus the qdiscs' init callback) is executed. In qdiscs that eventually call qdisc_tree_reduce_backlog during init or change (such as fq, hhf, choke, etc), an issue arises. For example, executing the following commands: sudo tc qdisc add dev lo root handle a: htb default 2 sudo tc qdisc add dev lo parent a: handle beef fq Qdiscs such as fq, hhf, choke, etc unconditionally invoke qdisc_tree_reduce_backlog() in their control path init() or change() which then causes a failure to find the child class; however, that does not stop the unconditional invocation of the assumed child qdisc's qlen_notify with a null class. All these qdiscs make the assumption that class is non-null. The solution is ensure that qdisc_leaf() which looks up the parent class, and is invoked prior to qdisc_create(), should return failure on not finding the class. In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the parentid doesn't correspond to a class, so that we can detect it earlier on and abort before qdisc_create is called. [1] https://lore.kernel.org/netdev/d912
CVE-2025-38457
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2025-38457
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "923a276c74e25073ae391e930792ac86a9f77f1e",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "90436e72c9622c2f70389070088325a3232d339f",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "25452638f133ac19d75af3f928327d8016952c8e",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "23c165dde88eac405eebb59051ea1fe139a45803",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "4c691d1b6b6dbd73f30ed9ee7da05f037b0c49af",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "8ecd651ef24ab50123692a4e3e25db93cb11602a",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "e28a383d6485c3bb51dc5953552f76c4dea33eea",
"versionType": "git"
},
{
"status": "affected",
"version": "5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6",
"lessThan": "ffdde7bf5a439aaa1955ebd581f5c64ab1533963",
"versionType": "git"
}
],
"programFiles": [
"net/sched/sch_api.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.20"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.20",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.4.296",
"versionType": "semver",
"lessThanOrEqual": "5.4.*"
},
{
"status": "unaffected",
"version": "5.10.240",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.189",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.146",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.99",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.39",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.15.7",
"versionType": "semver",
"lessThanOrEqual": "6.15.*"
},
{
"status": "unaffected",
"version": "6.16",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sched/sch_api.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-38457
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #27038 · Revision 1
- Added to Heist Feed
- Publisher date