Re: bin/45661: Overlapping buffer in route.c

[Christian Biere <christianbiere%gmx.de@localhost>]

The following reply was made to PR bin/45661; it has been noted by GNATS.

From: Christian Biere <christianbiere%gmx.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: bin/45661: Overlapping buffer in route.c
Date: Sun, 27 Nov 2011 14:02:13 +0100

 Unless I'm missing something the provided patch is incorrect
 because "len" is never updated inside the loop. However, I
 suggest using strlcat() instead to avoid pointer arithmetics
 with the destination buffer.
 
 There's also a similar issue in routename() which uses
 strlcpy() with overlapping memory.
 
 While we're at it, I also suggest fixing the alignment issues
 in three places.
 
 --- route.c.orig       2011-11-27 13:09:13.328002503 +0100
 +++ route.c    2011-11-27 13:57:01.928002817 +0100
 @@ -49,6 +49,7 @@ __RCSID("$NetBSD: route.c,v 1.134 2011/1
  #include <sys/ioctl.h>
  #include <sys/mbuf.h>
  #include <sys/sysctl.h>
 +#include <sys/endian.h>
  
  #include <net/if.h>
  #include <net/route.h>
 @@ -484,7 +485,7 @@ routename(const struct sockaddr *sa, str
                first = 0;
                if (gethostname(domain, MAXHOSTNAMELEN) == 0 &&
                    (cp = strchr(domain, '.')))
 -                      (void)strlcpy(domain, cp + 1, sizeof(domain));
 +                      memmove(domain, &cp[1], strlen(cp) + 1);
                else
                        domain[0] = 0;
        }
 @@ -550,7 +551,7 @@ routename(const struct sockaddr *sa, str
                     IN6_IS_ADDR_MC_LINKLOCAL(&sin6.sin6_addr)) &&
                    sin6.sin6_scope_id == 0) {
                        sin6.sin6_scope_id =
 -                          ntohs(*(u_int16_t *)&sin6.sin6_addr.s6_addr[2]);
 +                          be16dec(&sin6.sin6_addr.s6_addr[2]);
                        sin6.sin6_addr.s6_addr[2] = 0;
                        sin6.sin6_addr.s6_addr[3] = 0;
                }
 @@ -593,17 +594,19 @@ routename(const struct sockaddr *sa, str
                union mpls_shim ms;
                const union mpls_shim *pms;
                int psize = sizeof(struct sockaddr_mpls);
 +              char label[32];
  
                ms.s_addr =((const struct sockaddr_mpls*)sa)->smpls_addr.s_addr;
                ms.s_addr = ntohl(ms.s_addr);
  
 -              snprintf(line, sizeof(line), "%u", ms.shim.label);
 +              line[0] = '\0';
 +              snprintf(label, sizeof label, "%u", ms.shim.label);
                pms = &((const struct sockaddr_mpls*)sa)->smpls_addr;
                while(psize < sa->sa_len) {
                        pms++;
                        ms.s_addr = ntohl(pms->s_addr);
 -                      snprintf(line, sizeof(line), "%s %u", line,
 -                          ms.shim.label);
 +                      snprintf(label, sizeof label, " %u", ms.shim.label);
 +                      strlcat(line, sizeof line, label);
                        psize += sizeof(ms);
                }
                break;
 @@ -716,7 +719,7 @@ netname(const struct sockaddr *sa, struc
                     IN6_IS_ADDR_MC_LINKLOCAL(&sin6.sin6_addr)) &&
                    sin6.sin6_scope_id == 0) {
                        sin6.sin6_scope_id =
 -                          ntohs(*(u_int16_t *)&sin6.sin6_addr.s6_addr[2]);
 +                              be16dec(&sin6.sin6_addr.s6_addr[2]);
                        sin6.sin6_addr.s6_addr[2] = 0;
                        sin6.sin6_addr.s6_addr[3] = 0;
                }
 @@ -1270,8 +1273,8 @@ getaddr(int which, const char *s, struct
                if ((IN6_IS_ADDR_LINKLOCAL(&su->sin6.sin6_addr) ||
                     IN6_IS_ADDR_MC_LINKLOCAL(&su->sin6.sin6_addr)) &&
                    su->sin6.sin6_scope_id) {
 -                      *(u_int16_t *)&su->sin6.sin6_addr.s6_addr[2] =
 -                              htons(su->sin6.sin6_scope_id);
 +                      be16enc(&su->sin6.sin6_addr.s6_addr[2],
 +                              su->sin6.sin6_scope_id);
                        su->sin6.sin6_scope_id = 0;
                }
  #endif