conditional jump depends on uninitialised value in __libc_res_nsend

[Dan Kegel]

Running the (32-bit) chromium ui_tests all day under valgrind on
64 bit jaunty netted a single instance of this warning:

Conditional jump or move depends on uninitialised value(s)
   at __libc_res_nsend (res_send.c:1011)
   by __libc_res_nquery (res_query.c:225)
   by __libc_res_nquerydomain (res_query.c:569)
   by __libc_res_nsearch (res_query.c:370)
   by _nss_dns_gethostbyname3_r (dns-host.c:197)
   by _nss_dns_gethostbyname2_r (dns-host.c:245)
   by gethostbyname2_r@@GLIBC_2.1.2 (getXXbyYY_r.c:253)
   by gaih_inet (getaddrinfo.c:531)
   by getaddrinfo (getaddrinfo.c:2154)

Looking at the source for glibc in ia32-libs-2.7ubuntu6, I see
   1009 if (n == 0) {
   1010 Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
   1011 if (resplen > 1 && (recvresp1 || (buf2 != NULL && recvresp2)))
Sure enough, resplen isn't obviously initialized, either in this version of
glibc (2.9) or in glibc from git. I think it may be an upstream problem still.
Perhaps this occurs infrequently because DNS usually doesn't time out.

[Dan Kegel (dank)]

Filed upstream as http://sourceware.org/bugzilla/show_bug.cgi?id=10391