Re: [PATCH v2] kernel: kallsyms: memory override issue, need checkdestination buffer length

[Chen Gang]

On 2013å04æ15æ 10:05, Rusty Russell wrote:
> Chen Gang <gang.chen@xxxxxxxxxxx> writes:
>> >   We don't export any symbols > 128 characters, but if we did then
>> >   kallsyms_expand_symbol() would overflow the buffer handed to it.
>> >   So we need check destination buffer length when copying.
>> >
>> >   the related test:
>> >     if we define an EXPORT function which name more than 128.
>> >     will panic when call kallsyms_lookup_name by init_kprobes on booting.
>> >     after check the length (provide this patch), it is ok.
>> >
>> >   Implementaion:
>> >     add additional destination buffer length parameter (maxlen)
>> >     if uncompressed string is too long (>= maxlen), it will be truncated.
>> >     not check the parameters whether valid, since it is a static function.
> Found a bug already:
> 
> kernel/kallsyms.c: In function âkallsyms_lookupâ:
> kernel/kallsyms.c:305:78: error: negative width in bit-field â<anonymous>â
> kernel/kallsyms.c: In function âlookup_symbol_nameâ:
> kernel/kallsyms.c:327:78: error: negative width in bit-field â<anonymous>â
> kernel/kallsyms.c: In function âlookup_symbol_attrsâ:
> kernel/kallsyms.c:346:69: error: negative width in bit-field â<anonymous>â
> 

  oh... it is my fault, I will send v3.

  I only tested kallsyms_on_each_symbol and kallsyms_lookup_name (they
were of cause OK). , not test others.

  ARRAY_SIZE is really valuable to help find bugs.

  and next, after code changes, I should compile it again, at least.

  :-)


> Cheers,


-- 
Chen Gang

Asianux Corporation
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