Bug 2426188 (CVE-2022-50855)

Summary: CVE-2022-50855 kernel: bpf: prevent leak of lsm program after failed attach
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A reference count leak was found in the BPF subsystem. When attaching a BPF LSM program to a cgroup fails validation, the program's reference count is not decremented, causing the BPF program to remain loaded indefinitely.
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Description OSIDB Bzimport 2025-12-30 13:15:14 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: prevent leak of lsm program after failed attach

In [0], we added the ability to bpf_prog_attach LSM programs to cgroups,
but in our validation to make sure the prog is meant to be attached to
BPF_LSM_CGROUP, we return too early if the check fails. This results in
lack of decrementing prog's refcnt (through bpf_prog_put)
leaving the LSM program alive past the point of the expected lifecycle.
This fix allows for the decrement to take place.

[0] https://lore.kernel.org/all/20220628174314.1216643-4-sdf@google.com/
Comment 1 Alexander B 2025-12-31 02:47:18 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025123046-CVE-2022-50855-7845@gregkh/T