CVE-2022-50219 — linux / linux_kernel
Use After FreeIn 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.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 5.7 | 5.10.138 |
| linux / linux_kernel | 5.11 | 5.15.61 |
| linux / linux_kernel | 5.16 | 5.18.18 |
| linux / linux_kernel | 5.19 | 5.19.2 |
- 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
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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
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