CVE-2022-50219: bpf: Fix KASAN use-after-free Read in compute_effective_progs

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-06-18 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix KASAN use-after-free Read in compute_effective_progs Syzbot found a Use After Free bug in compute_effective_progs(). The reproducer creates a number of BPF links, and causes a fault injected alloc to fail, while calling bpf_link_detach on them. Link detach triggers the link to be freed by bpf_link_free(), which calls __cgroup_bpf_detach() and update_effective_progs(). If the memory allocation in this function fails, the function restores the pointer to the bpf_cgroup_link on the cgroup list, but the memory gets freed just after it returns. After this, every subsequent call to update_effective_progs() causes this already deallocated pointer to be dereferenced in prog_list_length(), and triggers KASAN UAF error. To fix this issue don't preserve the pointer to the prog or link in the list, but remove it and replace it with a dummy prog without shrinking the table. The subsequent call to __cgroup_bpf_detach() or __cgroup_bpf_detach() will correct it.

Affected products

Linux kernel: from 5.7 before 5.10.138; from 5.11 before 5.15.61; from 5.16 before 5.18.18; from 5.19 before 5.19.2 — fixed in 5.10.138, 5.15.61, 5.18.18, 5.19.2

How to fix

Upgrade to a fixed version: Linux kernel 5.10.138, 5.15.61, 5.18.18, 5.19.2. Check the vendor advisory for mitigations.

References

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