CVE-2022-49697

bpf: Fix request_sock leak in sk lookup helpers

Published Feb 26, 2025 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2022-54538 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.
History
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-401
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.19:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.19:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.19:rc3:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Type Values Removed Values Added
First Time appeared Redhat
Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
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.
Title bpf: Fix request_sock leak in sk lookup helpers
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
May 11, 2026, 7:04 PM
Reserved
Feb 26, 2025, 2:21 AM
Status
Analyzed
Published
Feb 26, 2025, 7:01 AM
Modified
Jun 17, 2026, 5:18 AM
Severity
Moderate
Public date
Feb 26, 2025, 12:00 AM