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Re: [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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[PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-19 15:00 +0200
  Re: [PATCH v3 3/7] kprobes: validate the symbol name length Masami Hiramatsu <mhiramat@kernel.org> - 2017-04-19 17:40 +0200
    Re: [PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-19 18:40 +0200
      Re: [PATCH v3 3/7] kprobes: validate the symbol name length Masami Hiramatsu <mhiramat@kernel.org> - 2017-04-21 15:50 +0200
        Re: [PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-23 17:50 +0200
  Re: [PATCH v3 3/7] kprobes: validate the symbol name length Michael Ellerman <mpe@ellerman.id.au> - 2017-04-20 08:10 +0200
    Re: [PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-20 09:30 +0200
  [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup_name() "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-21 14:40 +0200
    Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() Paul Clarke <pc@us.ibm.com> - 2017-04-21 15:40 +0200
      Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() Paul Clarke <pc@us.ibm.com> - 2017-04-21 15:40 +0200
      Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() Paul Clarke <pc@us.ibm.com> - 2017-04-21 16:00 +0200
        Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-23 19:20 +0200
  [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-21 14:40 +0200
    Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during  probe registration Paul Clarke <pc@us.ibm.com> - 2017-04-21 15:20 +0200
      Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during  probe registration "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-21 15:30 +0200
    Re: [PATCH v4 3/7] kprobes: validate the symbol name provided  during probe registration Masami Hiramatsu <mhiramat@kernel.org> - 2017-04-21 16:00 +0200
    Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration Michael Ellerman <mpe@ellerman.id.au> - 2017-04-22 08:00 +0200
      Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during  probe registration "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-23 19:50 +0200

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