On Thu, Dec 16, 2021 at 4:32 PM Hao Luo <haoluo@xxxxxxxxxx> wrote: > > Some helper functions may modify its arguments, for example, > bpf_d_path, bpf_get_stack etc. Previously, their argument types > were marked as ARG_PTR_TO_MEM, which is compatible with read-only > mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate > to modify a read-only memory by passing it into one of such helper > functions. I've added ", but technically incorrect" to the above sentence. Otherwise it sounds like it was an ok thing to do. I've considered adding a set of Fixes tag, but there would be too many and it's a laborious task to look through all such helpers just to beautify the commit log. This patch set isn't going to be backported anyway due to complexity. Please add a test to make sure that bpf_d_path on rdonly buf is rejected. Thank you very much for doing this work. It's a great improvement to the verifier type handling. There is a concern that generality of flags may cause a regression, but no amount of code review will reveal that. Please watch out for strange verifier issues.
