In the Linux kernel, the following vulnerability has been resolved:
net_sched: hfsc: Fix a UAF vulnerability in class handling
This patch fixes a Use-After-Free vulnerability in the HFSC qdisc class
handling. The issue occurs due to a time-of-check/time-of-use condition
in hfsc_change_class() when working with certain child qdiscs like netem
or codel.
The vulnerability works as follows:
1. hfsc_change_class() checks if a class has packets (q.qlen != 0)
2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g.,
codel, netem) might drop packets and empty the queue
3. The code continues assuming the queue is still non-empty, adding
the class to vttree
4. This breaks HFSC scheduler assumptions that only non-empty classes
are in vttree
5. Later, when the class is destroyed, this can lead to a Use-After-Free
The fix adds a second queue length check after qdisc_peek_len() to verify
the queue wasn't emptied.
References
Configurations
Configuration 1 (hide)
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Configuration 2 (hide)
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History
No history.
Information
Published : 2025-05-02 15:15
Updated : 2025-11-06 20:48
NVD link : CVE-2025-37797
Mitre link : CVE-2025-37797
CVE.ORG link : CVE-2025-37797
JSON object : View
Products Affected
debian
- debian_linux
linux
- linux_kernel
CWE
CWE-416
Use After Free
