Vulnerability Database

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Total vulnerabilities in the database

CVE-2024-35910 — linux / linux_kernel

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

tcp: properly terminate timers for kernel sockets

We had various syzbot reports about tcp timers firing after the corresponding netns has been dismantled.

Fortunately Josef Bacik could trigger the issue more often, and could test a patch I wrote two years ago.

When TCP sockets are closed, we call inet_csk_clear_xmit_timers() to 'stop' the timers.

inet_csk_clear_xmit_timers() can be called from any context, including when socket lock is held. This is the reason it uses sk_stop_timer(), aka del_timer(). This means that ongoing timers might finish much later.

For user sockets, this is fine because each running timer holds a reference on the socket, and the user socket holds a reference on the netns.

For kernel sockets, we risk that the netns is freed before timer can complete, because kernel sockets do not hold reference on the netns.

This patch adds inet_csk_clear_xmit_timers_sync() function that using sk_stop_timer_sync() to make sure all timers are terminated before the kernel socket is released. Modules using kernel sockets close them in their netns exit() handler.

Also add sock_not_owned_by_me() helper to get LOCKDEP support : inet_csk_clear_xmit_timers_sync() must not be called while socket lock is held.

It is very possible we can revert in the future commit 3a58f13a881e ("net: rds: acquire refcount on TCP sockets") which attempted to solve the issue in rds only. (net/smc/af_smc.c and net/mptcp/subflow.c have similar code)

We probably can remove the check_net() tests from tcp_out_of_resources() and __tcp_close() in the future.

  • Published: May 19, 2024
  • Updated: Nov 16, 2025
  • CVE: CVE-2024-35910
  • Severity: Medium
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: Medium
  • Score: 5.8
  • AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H

No CWE or OWASP classifications available.

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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

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