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 <s...@spacehopper.org>
> 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?
Anyway, I went and looked on the spec for the 't' display hint in rfc2579
ยง3.1 and it explicitly states that unterminated utf-8 characters at the end
of an t encoded octet string are to be discarded.
Looking at the code surrounding this chunk seems to suggest that some TLC for
the 't' display hint could be useful.
> + memcpy(*buf + *out_len, cp, cnt);
In any case I have to admit that the functional part of the patch (use memcpy
rather than strlcpy to copy possibly not null terminated data) is good so
+1 for this part
/MF
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