CVE-2024-26740: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mirred: use the backlog for mirred ingress The test Davide added in commit ca22da2fbd69 ("act_mirred: use the backlog for nested calls to mirred ingress") hangs our testing VMs every 10 or so runs, with the familiar tcp_v4_rcv -> tcp_v4_rcv deadlock reported by lockdep. The problem as previously described by Davide (see Link) is that if we reverse flow of traffic with the redirect (egress -> ingress) we may reach the same socket which generated the packet. And we may still be holding its socket lock. The common solution to such deadlocks is to put the packet in the Rx backlog, rather than run the Rx path inline. Do that for all egress -> ingress reversals, not just once we started to nest mirred calls. In the past there was a concern that the backlog indirection will lead to loss of error reporting / less accurate stats. But the current workaround does not seem to address the issue.

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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-667 CWE-667

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.10 — 6.6.19
linux	linux_kernel	6.7 — 6.7.7
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/52f671db18823089a02f07efc04efdb2272ddc17 https://git.kernel.org/stable/c/60ddea1600bc476e0f5e02bce0e29a460ccbf0be https://git.kernel.org/stable/c/7c787888d164689da8b1b115f3ef562c1e843af4 https://git.kernel.org/stable/c/52f671db18823089a02f07efc04efdb2272ddc17 https://git.kernel.org/stable/c/60ddea1600bc476e0f5e02bce0e29a460ccbf0be https://git.kernel.org/stable/c/7c787888d164689da8b1b115f3ef562c1e843af4

Frequently Asked Questions

What is CVE-2024-26740? +

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mirred: use the backlog for mirred ingress The test Davide added in commit ca22da2fbd69 ("act_mirred: use the backlog for nested calls to mirred ingress") hangs our testing VMs every 10 or so runs, with the familiar tcp_v4_rcv -> tcp_v4_rcv deadlock reported by lockdep. The problem as previously described by Davide (see Link) is that if we reverse flow of traffic with the redirect (egress -> ingress) we may reach the same socket which generated the packet. And we may still be holding its socket lock. The common solution to such deadlocks is to put the packet in the Rx backlog, rather than run the Rx path inline. Do that for all egress -> ingress reversals, not just once we started to nest mirred calls. In the past there was a concern that the backlog indirection will lead to loss of error reporting / less accurate stats. But the current workaround does not seem to address the issue. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2024-26740? +

CVE-2024-26740 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-2024-26740? +

CVE-2024-26740 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-2024-26740? +

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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CVE-2024-26740