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

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 */
+                        memcpy(*buf + *out_len, cp, cnt);
                         *out_len += cnt;
+                        *(*buf + *out_len) = '\0';
                     } else if (!sprint_realloc_asciistring(buf, buf_len,
                                      out_len, allow_realloc, cp, cnt)) {
                         return 0;
-- 
2.16.3


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