net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc
As described in Gerrard's report [1], we have a UAF case when an hfsc class
has a netem child qdisc. The crux of the issue is that hfsc is assuming
that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted
the class in the vttree or eltree (which is not true for the netem
duplicate case).
This patch checks the n_active class variable to make sure that the code
won't insert the class in the vttree or eltree twice, catering for the
reentrant case.
[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
Metrics
Affected Vendors & Products
| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-4271-1 | linux-6.1 security update |
Debian DLA |
DLA-4327-1 | linux security update |
Debian DSA |
DSA-5925-1 | linux security update |
EUVD |
EUVD-2025-15440 | In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/ |
Ubuntu USN |
USN-7608-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7608-2 | Linux kernel (FIPS) vulnerabilities |
Ubuntu USN |
USN-7608-3 | Linux kernel (Real-time) vulnerabilities |
Ubuntu USN |
USN-7608-4 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7608-5 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7608-6 | Linux kernel (Xilinx ZynqMP) vulnerabilities |
Ubuntu USN |
USN-7608-7 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7609-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7609-2 | Linux kernel (Real-time) vulnerabilities |
Ubuntu USN |
USN-7609-3 | Linux kernel (IBM) vulnerabilities |
Ubuntu USN |
USN-7609-4 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7609-5 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7610-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7610-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7610-3 | Linux kernel (Low Latency) vulnerabilities |
Ubuntu USN |
USN-7611-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7611-2 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7611-3 | Linux kernel (AWS) vulnerabilities |
Ubuntu USN |
USN-7611-4 | Linux kernel (Oracle) vulnerabilities |
Ubuntu USN |
USN-7618-1 | Linux kernel (OEM) vulnerabilities |
Ubuntu USN |
USN-7628-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7653-1 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-7655-1 | Linux kernel (Intel IoTG) vulnerabilities |
Ubuntu USN |
USN-7665-2 | Linux kernel (AWS) vulnerabilities |
Ubuntu USN |
USN-7671-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7671-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7671-3 | Linux kernel (IoT) vulnerabilities |
Ubuntu USN |
USN-7686-1 | Linux kernel (Raspberry Pi) vulnerabilities |
Ubuntu USN |
USN-7712-1 | Linux kernel (Azure FIPS) vulnerabilities |
Ubuntu USN |
USN-7712-2 | Linux kernel (Azure) vulnerabilities |
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Mon, 17 Nov 2025 17:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Debian
Debian debian Linux |
|
| Weaknesses | CWE-416 | |
| CPEs | cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:-:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:rc7:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.0:rc8:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.15:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.15:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.15:rc4:*:*:*:*:*:* |
|
| Vendors & Products |
Debian
Debian debian Linux |
|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Mon, 03 Nov 2025 20:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Mon, 03 Nov 2025 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Wed, 18 Jun 2025 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Thu, 12 Jun 2025 19:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Wed, 04 Jun 2025 13:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Tue, 20 May 2025 02:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 16 May 2025 13:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/ | |
| Title | net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc | |
| References |
|
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-11-03T19:57:02.260Z
Reserved: 2025-04-16T04:51:23.963Z
Link: CVE-2025-37890
No data.
Status : Analyzed
Published: 2025-05-16T13:15:52.437
Modified: 2025-11-17T17:11:57.840
Link: CVE-2025-37890
OpenCVE Enrichment
Updated: 2025-06-23T19:32:00Z
Debian DLA
Debian DSA
EUVD
Ubuntu USN