Re: [PATCH; request for votes] snmplib: Avoid that sprint_realloc_octet_string() triggers a segmentation fault

On 05/19/18 15:14, Magnus Fromreide wrote:
> On Sat, May 19, 2018 at 02:07:56PM -0700, Bart Van Assche wrote:
>> strlcpy() implementations typically scan for the end of the source argument
>> passed to strlcpy(). Hence avoid passing an unterminated string to strlcpy().
>>
>> Reported-by: Stuart Henderson <[email protected]>
>> Fixes: 7f05daa8e0e0 ("CHANGES: BUG: 3444939: BUG: 1796886: snmplib: Avoid that sprint_realloc_octet_string() embeds unprintable control characters or binary zeroes in its output. This behavior could cause truncated output in snmptrapd.")
>> ---
>>   snmplib/mib.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/snmplib/mib.c b/snmplib/mib.c
>> index a16144065029..1c875c06464f 100644
>> --- a/snmplib/mib.c
>> +++ b/snmplib/mib.c
>> @@ -585,9 +585,10 @@ sprint_realloc_octet_string(u_char ** buf, size_t * buf_len,
>>                               return 0;
>>                       }
>>                       if (memchr(cp, '\0', cnt) == NULL) {
>> -                        /* No embedded '\0' - use strlcpy() to preserve UTF-8 */
>> -                        strlcpy((char *)(*buf + *out_len), (char *)cp, cnt + 1);
>> +                        /* No embedded '\0' - use memcpy() to preserve UTF-8 */
> 
> The comment does not make any sense - what have UTF-8 got to do with this?

Hello Magnus,

Does this mean that you did not understand that comment? The code under 
the else-clause does not preserve UTF-8 (sprint_realloc_asciistring()). 
Hence the comment in the if-clause about preserving UTF-8.

Bart.


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