CVE-2024-42108: linux kernel Use-After-Free — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: net: rswitch: Avoid use-after-free in rswitch_poll() The use-after-free is actually in rswitch_tx_free(), which is inlined in rswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the same pointer, the skb is first freed using dev_kfree_skb_any(), then the value in skb->len is used to update the interface statistics. Let's move around the instructions to use skb->len before the skb is freed. This bug is trivial to reproduce using KFENCE. It will trigger a splat every few packets. A simple ARP request or ICMP echo request is enough.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.8 — 6.9.9

References

Advisories & Patches

https://git.kernel.org/stable/c/4a41bb9f2b402469d425a1c13359d3b3ea4e6403 https://git.kernel.org/stable/c/92cbbe7759193e3418f38d0d73f8fe125312c58b https://git.kernel.org/stable/c/9a0c28efeec6383ef22e97437616b920e7320b67 https://git.kernel.org/stable/c/92cbbe7759193e3418f38d0d73f8fe125312c58b https://git.kernel.org/stable/c/9a0c28efeec6383ef22e97437616b920e7320b67

Frequently Asked Questions

What is CVE-2024-42108? +

In the Linux kernel, the following vulnerability has been resolved: net: rswitch: Avoid use-after-free in rswitch_poll() The use-after-free is actually in rswitch_tx_free(), which is inlined in rswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the same pointer, the skb is first freed using dev_kfree_skb_any(), then the value in skb->len is used to update the interface statistics. Let's move around the instructions to use skb->len before the skb is freed. This bug is trivial to reproduce using KFENCE. It will trigger a splat every few packets. A simple ARP request or ICMP echo request is enough. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2024-42108? +

CVE-2024-42108 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-42108? +

CVE-2024-42108 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-42108? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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