"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error\n\nFor all non-tracing helpers which formerly had ARG_PTR_TO_{LONG,INT} as input\narguments, zero the value for the case of an error as otherwise it could leak\nmemory. For tracing, it is not needed given CAP_PERFMON can already read all\nkernel memory anyway hence bpf_get_func_arg() and bpf_get_func_ret() is skipped\nin here.\n\nAlso, the MTU helpers mtu_len pointer value is being written but also read.\nTechnically, the MEM_UNINIT should not be there in order to always force init.\nRemoving MEM_UNINIT needs more verifier rework though: MEM_UNINIT right now\nimplies two things actually: i) write into memory, ii) memory does not have\nto be initialized. If we lift MEM_UNINIT, it then becomes: i) read into memory,\nii) memory must be initialized. This means that for bpf_*_check_mtu() we're\nreadding the issue we're trying to fix, that is, it would then be able to\nwrite back into things like .rodata BPF maps. Follow-up work will rework the\nMEM_UNINIT semantics such that the intent can be better expressed. For now\njust clear the *mtu_len on error path which can be lifted later again."
