CVE-2025-37953

Source
https://nvd.nist.gov/vuln/detail/CVE-2025-37953
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-37953.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2025-37953
Downstream
Related
Published
2025-05-20T16:15:33Z
Modified
2025-08-28T15:15:47Z
Summary
[none]
Details

In the Linux kernel, the following vulnerability has been resolved:

schhtb: make htbdeactivate() idempotent

Alan reported a NULL pointer dereference in htbnextrbnode() after we made htbqlen_notify() idempotent.

It turns out in the following case it introduced some regression:

htbdequeuetree(): |-> fqcodeldequeue() |-> qdisctreereducebacklog() |-> htbqlennotify() |-> htbdeactivate() |-> htbnextrbnode() |-> htbdeactivate()

For htbnextrbnode(), after calling the 1st htbdeactivate(), the clprio[prio]->ptr could be already set to NULL, which means htbnextrb_node() is vulnerable here.

For htbdeactivate(), although we checked qlen before calling it, in case of qlen==0 after qdisctreereducebacklog(), we may call it again which triggers the warning inside.

To fix the issues here, we need to:

1) Make htbdeactivate() idempotent, that is, simply return if we already call it before. 2) Make htbnextrbnode() safe against ptr==NULL.

Many thanks to Alan for testing and for the reproducer.

References

Affected packages