Re: [PATCH] libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc: Avoid writing '\0' out of string's border

[Chen Gang <gang.chen.5i5j@gmail.com>]

On 08/28/2014 06:51 AM, Konstantin Serebryany wrote:
> [replying text only]
> 
> Hi Chen,
> as per https://code.google.com/p/address-sanitizer/wiki/HowToContribute
> all changes to libsanitizer, even such simple ones,
> have to go through the LLVM tree first.
> 

OK, thanks, I shall notice about it, next.

> But, what makes you think there is a bug here?
> The comment in sanitizer_common/sanitizer_common.h says:
> // name should have space for at least max_len+1 bytes.
> 

Oh, really, but for me, I still prefer to let max_len as all real buffer
length which like common sense (especially for extern functions).

If this extern function is not real used, at present (but will be used
next), for me, I still want to improve it (about max_len).


Thanks.

> --kcc
> 
> On Wed, Aug 27, 2014 at 3:43 PM, Chen Gang <gang.chen.5i5j@gmail.com> wrote:
>> 'max_len' is the maximized length of 'name', so for writing '\0' to
>> "name[max_len]", it is out of string's border, need use "max_len - 1"
>> instead of.
>>
>> Pass normal test suite: "configure && make && make check && compare",
>> I guess, at present, it is not really used by outside, though.
>>
>> 2014-08-27  Chen Gang  <gang.chen.5i5j@gmail.com>
>>
>>         * sanitizer_common/sanitizer_linux_libcdep.cc
>>         (SanitizerGetThreadName): Avoid writing '\0' out of string's
>>         border
>> ---
>>  libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc b/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc
>> index e754b26..b9089d5 100644
>> --- a/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc
>> +++ b/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc
>> @@ -140,7 +140,7 @@ bool SanitizerGetThreadName(char *name, int max_len) {
>>    if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0))  // NOLINT
>>      return false;
>>    internal_strncpy(name, buff, max_len);
>> -  name[max_len] = 0;
>> +  name[max_len - 1] = 0;
>>    return true;
>>  #else
>>    return false;
>> --
>> 1.9.3


-- 
Chen Gang

Open share and attitude like air water and life which God blessed