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SubjectRe: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration
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"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> 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

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