On Mar 24 2024, Alexei Starovoitov wrote: > On Sat, Mar 23, 2024 at 9:57 PM Kumar Kartikeya Dwivedi > <memxor@xxxxxxxxx> wrote: > > > > > > > > > > > Observation is correct. The patch is buggy, > > > > > but the suggestion to follow process_dynptr_func() will lead > > > > > to unnecessary complexity. > > > > > dynptr-s are on stack with plenty of extra checks. > > > > > > > > The suggestion was to call process_timer_func, not process_dynptr_func. > > > > > > > > > In this case bpf_timer is in map_value. > > > > > Much simpler is to follow KF_ARG_PTR_TO_MAP approach. > > > > > > > > What I meant by the example was that dynptr handling does the same > > > > thing for kfuncs and helpers (using the same function), so timer > > > > arguments should do the same (i.e. use process_timer_func), which will > > > > do all checks for constant offset (ensuring var_off is tnum_is_const) > > > > and match it against btf_record->timer_off. > > > > > > I don't follow. Please elaborate with a patch. > > > The var_off and off is a part of the bug, but it's not the biggest part of it. > > > > Not compile tested. Compiles just fine :) > > I see. All makes sense to me. > > Benjamin, > pls incorporate it in your set. > OK, done! I just had to revert to the following or KF_ARG_TIMER_ID was not recognized by the verifier: --- diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7ee20e9d14bd..a5e147468ac8 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10848,7 +10848,7 @@ BTF_ID(struct, bpf_list_head) BTF_ID(struct, bpf_list_node) BTF_ID(struct, bpf_rb_root) BTF_ID(struct, bpf_rb_node) -BTF_ID(struct, bpf_timer) +BTF_ID(struct, bpf_timer_kern) static bool __is_kfunc_ptr_arg_type(const struct btf *btf, const struct btf_param *arg, int type) --- Cheers, Benjamin
