CVE-2022-50219 Information

Jun 19, 2025 cve

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.

Reference

https://git.kernel.org/stable/c/1f8ca9c40e6222ce431e9ba5dae3cccce8ef9443 https://git.kernel.org/stable/c/3527e3cbb84d8868c4d4e91ba55915f96d39ec3d https://git.kernel.org/stable/c/4c46091ee985ae84c60c5e95055d779fcd291d87 https://git.kernel.org/stable/c/6336388715afa419cc97d0255bda3bba1b96b7ca https://git.kernel.org/stable/c/be001f9da71eaa3b61e186fb88bde3279728bdca

CNNVD-202506-2509 (Published: 2025-06-18)

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