fix h_alias handling in gethostbyaddr_r() just like in gethostbyname_r()

otherwise we get messed up alias memory and this simple test case will
segfault:
python -c 'import socket; print socket.gethostbyaddr("80.68.88.204")[2];'

see bug report in blackfin tracker for more info:
http://blackfin.uclinux.org/tracker/index.php?func=detail&aid=1503&group_id=17&atid=141

diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 560c569..26d68d2 100644 (file)
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -2259,6 +2259,7 @@ int gethostbyaddr_r (const void *addr, socklen_t len, int type,
        struct in6_addr *in6;
        struct in6_addr **addr_list6;
 #endif /* __UCLIBC_HAS_IPV6__ */
+       char **alias;
        unsigned char *packet;
        struct resolv_answer a;
        int i;
@@ -2319,6 +2320,12 @@ int gethostbyaddr_r (const void *addr, socklen_t len, int type,
        buf+=sizeof(*addr_list)*2;
        buflen-=sizeof(*addr_list)*2;
 
+       if (buflen < sizeof(char *)*(ALIAS_DIM))
+               return ERANGE;
+       alias=(char **)buf;
+       buf+=sizeof(*alias)*(ALIAS_DIM);
+       buflen-=sizeof(*alias)*(ALIAS_DIM);
+
 #ifdef __UCLIBC_HAS_IPV6__
        if (plen < sizeof(*in6))
                return ERANGE;
@@ -2367,6 +2374,9 @@ int gethostbyaddr_r (const void *addr, socklen_t len, int type,
 
        addr_list[1] = 0;
 
+       alias[0] = buf;
+       alias[1] = 0;
+
        for (;;) {
 
        BIGLOCK;
@@ -2413,6 +2423,7 @@ int gethostbyaddr_r (const void *addr, socklen_t len, int type,
                }
 
                        result_buf->h_addr_list = (char **) addr_list;
+                       result_buf->h_aliases = alias;
                        break;
                } else {
                        free(packet);