net_sched: hfsc: Address reentrant enqueue adding class to eltree twice
In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Address reentrant enqueue adding class to eltree twice Savino says: "We are writing to report that this recent patch (141d34391abbb315d68556b7c67ad97885407547) [1] can be bypassed, and a UAF can still occur when HFSC is utilized with NETEM. The patch only checks the cl->cl_nactive field to determine whether it is the first insertion or not [2], but this field is only incremented by init_vf [3]. By using HFSC_RSC (which uses init_ed) [4], it is possible to bypass the check and insert the class twice in the eltree. Under normal conditions, this would lead to an infinite loop in hfsc_dequeue for the reasons we already explained in this report [5]. However, if TBF is added as root qdisc and it is configured with a very low rate, it can be utilized to prevent packets from being dequeued. This behavior can be exploited to perform subsequent insertions in the HFSC eltree and cause a UAF." To fix both the UAF and the infinite loop, with netem as an hfsc child, check explicitly in hfsc_enqueue whether the class is already in the eltree whenever the HFSC_RSC flag is set. [1] https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=141d34391abbb315d68556b7c67ad97885407547 [2] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L1572 [3] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L677 [4] https://elixir.bootlin.com/linux/v6.15-rc5/so
CVE-2025-38001
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-2025-38001
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": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "e5bee633cc276410337d54b99f77fbc1ad8801e5",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "6672e6c00810056acaac019fe26cdc26fee8a66c",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "2c928b3a0b04a431ffcd6c8b7d88a267124a3a28",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "a0ec22fa20b252edbe070a9de8501eef63c17ef5",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "295f7c579b07b5b7cf2dffe485f71cc2f27647cb",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "2f2190ce4ca972051cac6a8d7937448f8cb9673c",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "4e38eaaabfb7fffbb371a51150203e19eee5d70e",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "39ed887b1dd2d6b720f87e86692ac3006cc111c8",
"versionType": "git"
},
{
"status": "affected",
"version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
"lessThan": "ac9fe7dd8e730a103ae4481147395cc73492d786",
"versionType": "git"
}
],
"programFiles": [
"net/sched/sch_hfsc.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.0"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.4.294",
"versionType": "semver",
"lessThanOrEqual": "5.4.*"
},
{
"status": "unaffected",
"version": "5.10.238",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.185",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.141",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.93",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.32",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.14.10",
"versionType": "semver",
"lessThanOrEqual": "6.14.*"
},
{
"status": "unaffected",
"version": "6.15.1",
"versionType": "semver",
"lessThanOrEqual": "6.15.*"
},
{
"status": "unaffected",
"version": "6.16",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sched/sch_hfsc.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-38001
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #30507 · Revision 1
- Added to Heist Feed
- Publisher date