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NULL Pointer Dereference The advisory has been revoked - it doesn't affect any version of package python-perf  (opens in a new tab)

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EPSS
0.03% (9th percentile)

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  • Snyk IDSNYK-CENTOS7-PYTHONPERF-10200057
  • published21 May 2025
  • disclosed20 May 2025
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Introduced: 20 May 2025

CVE-2025-37953  (opens in a new tab)
CWE-476  (opens in a new tab)

Amendment

The Centos security team deemed this advisory irrelevant for Centos:7.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python-perf package and not the python-perf package as distributed by Centos.

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

sch_htb: make htb_deactivate() idempotent

Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent.

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

htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate()

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

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

To fix the issues here, we need to:

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

Many thanks to Alan for testing and for the reproducer.