Hello Yafang Shao,
The patch 1b715e1b0ec5: "bpf: Support ->fill_link_info for
perf_event" from Jul 9, 2023, leads to the following Smatch static
checker warning:
kernel/bpf/syscall.c:3416 bpf_perf_link_fill_kprobe()
error: uninitialized symbol 'type'.
kernel/bpf/syscall.c
3402 static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
3403 struct bpf_link_info *info)
3404 {
3405 char __user *uname;
3406 u64 addr, offset;
3407 u32 ulen, type;
3408 int err;
3409
3410 uname = u64_to_user_ptr(info->perf_event.kprobe.func_name);
3411 ulen = info->perf_event.kprobe.name_len;
3412 err = bpf_perf_link_fill_common(event, uname, ulen, &offset, &addr,
3413 &type);
3414 if (err)
3415 return err;
--> 3416 if (type == BPF_FD_TYPE_KRETPROBE)
It looks like you could call bpf_get_perf_event_info() without it
initializing *fd_type to anything. Meanwhile if you initialize it to
zero here, that won't even affect the compiled code at all because
everyone zeroes stack data these days.
3417 info->perf_event.type = BPF_PERF_EVENT_KRETPROBE;
3418 else
3419 info->perf_event.type = BPF_PERF_EVENT_KPROBE;
3420
3421 info->perf_event.kprobe.offset = offset;
3422 if (!kallsyms_show_value(current_cred()))
3423 addr = 0;
3424 info->perf_event.kprobe.addr = addr;
3425 return 0;
3426 }
regards,
dan carpenter
