From ef9b259ae24e7bf4ebec04b0b0a44964bc661bb5 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Mon, 4 Feb 2013 12:43:08 +0100 Subject: [PATCH 8/8] Fix a segfault in nscd when using nss-myhostname MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Nscd expects that an NSS module's gethostbyname4_r function returns its first result in the pre-allocated gaih_addrtuple denoted by **pat. (See nscd/aicache.c in the Glibc sources.) However, nss-myhostname doesn't fill in **pat but allocates the first result in ‘buffer’, then sets *pat. So nscd crashes (e.g. when running ‘getent ahosts my-machine’). Hard to tell if this is a bug in nscd, since there doesn't seem to be a proper API spec for gethostbyname4_r. But in any case, this patch fixes the crash by copying the first result to **pat. --- src/nss-myhostname/nss-myhostname.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/nss-myhostname/nss-myhostname.c b/src/nss-myhostname/nss-myhostname.c index 834a806..b0fb832 100644 --- a/src/nss-myhostname/nss-myhostname.c +++ b/src/nss-myhostname/nss-myhostname.c @@ -176,7 +176,11 @@ enum nss_status _nss_myhostname_gethostbyname4_r( /* Verify the size matches */ assert(idx == ms); - *pat = r_tuple_prev; + /* Nscd expects us to store the first record in **pat. */ + if (*pat) + **pat = *r_tuple_prev; + else + *pat = r_tuple_prev; if (ttlp) *ttlp = 0; -- 1.8.1