"Naveen N. Rao" [off-list ref] writes:

When a kprobe is being registered, we use the symbol_name field to
lookup the address where the probe should be placed. Since this is a
user-provided field, let's ensure that the length of the string is
within expected limits.

What are we actually trying to protect against here?

If you ignore powerpc for a moment, kprobe_lookup_name() is just
kallsyms_lookup_name().

All kallsyms_lookup_name() does with name is strcmp() it against a
legitimate symbol name which is at most KSYM_NAME_LEN.

So I don't think any of this validation helps in that case?

In the powerpc version of kprobe_lookup_name() we do need to do some
string juggling, for which it helps to know the input is sane. But I
think we should just make that code more robust by checking the input
before we do anything with it.

cheers