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Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration

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a nit or two, below...

On 04/21/2017 07:32 AM, Naveen N. Rao wrote:
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 6a128f3a7ed1..ff9b1ac72a38 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1383,6 +1383,34 @@ bool within_kprobe_blacklist(unsigned long addr)
>  }
> 
>  /*
> + * We mainly want to ensure that the provided string is of a reasonable length
> + * and is of the form [<mod_name>:]<sym_name>, so that this is safe to process
> + * further.
> + * We don't worry about invalid characters as those will just prevent
> + * matching existing kallsyms.
> + */
> +bool is_valid_kprobe_symbol_name(const char *name)
> +{
> +	size_t sym_len;
> +	const char *s;
> +
> +	s = strnchr(name, ':', MODULE_NAME_LEN + KSYM_NAME_LEN + 1);
> +	if (s) {
> +		sym_len = (size_t)(s - name);
> +		if (sym_len <= 0  || sym_len >= MODULE_NAME_LEN)

"sym_len <= 0" looks odd here, since sym_len is likely unsigned and would never be less than zero, anyway.

> +			return false;
> +		s++;
> +	} else
> +		s = name;
> +
> +	sym_len = strnlen(s, KSYM_NAME_LEN);
> +	if (sym_len <= 0 || sym_len >= KSYM_NAME_LEN)

here, too.

> +		return false;
> +
> +	return true;
> +}

PC

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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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