bpf: Add MEM_WRITE attribute
Add a MEM_WRITE attribute for BPF helper functions which can be used in bpf_func_proto to annotate an argument type in order to let the verifier know that the helper writes into the memory passed as an argument. In the past MEM_UNINIT has been (ab)used for this function, but the latter merely tells the verifier that the passed memory can be uninitialized. There have been bugs with overloading the latter but aside from that there are also cases where the passed memory is read + written which currently cannot be expressed, see also 4b3786a6 ("bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error"). Signed-off-by:Daniel Borkmann <daniel@iogearbox.net> Acked-by:
Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net Signed-off-by:
Alexei Starovoitov <ast@kernel.org>
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- include/linux/bpf.h 11 additions, 3 deletionsinclude/linux/bpf.h
- kernel/bpf/helpers.c 5 additions, 5 deletionskernel/bpf/helpers.c
- kernel/bpf/ringbuf.c 1 addition, 1 deletionkernel/bpf/ringbuf.c
- kernel/bpf/syscall.c 1 addition, 1 deletionkernel/bpf/syscall.c
- kernel/trace/bpf_trace.c 2 additions, 2 deletionskernel/trace/bpf_trace.c
- net/core/filter.c 2 additions, 2 deletionsnet/core/filter.c
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