CVE-2022-49697: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix request_sock leak in sk lookup helpers A customer reported a request_socket leak in a Calico cloud environment. We found that a BPF program was doing a socket lookup with takes a refcnt on the socket and that it was finding the request_socket but returning the parent LISTEN socket via sk_to_full_sk() without decrementing the child request socket 1st, resulting in request_sock slab object leak. This patch retains the existing behaviour of returning full socks to the caller but it also decrements the child request_socket if one is present before doing so to prevent the leak. Thanks to Curtis Taylor for all the help in diagnosing and testing this. And thanks to Antoine Tenart for the reproducer and patch input. v2 of this patch contains, refactor as per Daniel Borkmann's suggestions to validate RCU flags on the listen socket so that it balances with bpf_sk_release() and update comments as per Martin KaFai Lau's suggestion. One small change to Daniels suggestion, put "sk = sk2" under "if (sk2 != sk)" to avoid an extra instruction.

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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-401 CWE-401

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.2 — 5.4.202
linux	linux_kernel	5.5 — 5.10.127
linux	linux_kernel	5.11 — 5.15.51
linux	linux_kernel	5.16 — 5.18.8
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/3046a827316c0e55fc563b4fb78c93b9ca5c7c37 https://git.kernel.org/stable/c/516760f1d2979903eaad5b437256913c5cd98416 https://git.kernel.org/stable/c/5a62b5ba4c0ce8315b6382cd4ace81b48cd121cd https://git.kernel.org/stable/c/8ffe2e50e9678c8373027492035f094b130437f1 https://git.kernel.org/stable/c/b03607437ea81b850599f705096b05b85e7a4a71

Frequently Asked Questions

What is CVE-2022-49697? +

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix request_sock leak in sk lookup helpers A customer reported a request_socket leak in a Calico cloud environment. We found that a BPF program was doing a socket lookup with takes a refcnt on the socket and that it was finding the request_socket but returning the parent LISTEN socket via sk_to_full_sk() without decrementing the child request socket 1st, resulting in request_sock slab object leak. This patch retains the existing behaviour of returning full socks to the caller but it also decrements the child request_socket if one is present before doing so to prevent the leak. Thanks to Curtis Taylor for all the help in diagnosing and testing this. And thanks to Antoine Tenart for the reproducer and patch input. v2 of this patch contains, refactor as per Daniel Borkmann's suggestions to validate RCU flags on the listen socket so that it balances with bpf_sk_release() and update comments as per Martin KaFai Lau's suggestion. One small change to Daniels suggestion, put "sk = sk2" under "if (sk2 != sk)" to avoid an extra instruction. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2022-49697? +

CVE-2022-49697 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-2022-49697? +

CVE-2022-49697 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-2022-49697? +

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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