From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 27 Apr 2016 15:15:57 +0000 (+0200)
Subject: nss_dns: Skip over non-PTR records in the netent code [BZ #19868]
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=742bcfaa70ea522406dd046adafefa933d29ca50;p=thirdparty%2Fglibc.git

nss_dns: Skip over non-PTR records in the netent code [BZ #19868]

This requires additional checks for the RDATA length and the
availability of record metadata.

(cherry picked from commit a12f9431b3808e78b9ed397e4fce7de69410d94d)
(cherry picked from commit 1e5ac8a1daa360cd9632e5056e4bdf29e18ac2c7)
---

diff --git a/resolv/nss_dns/dns-network.c b/resolv/nss_dns/dns-network.c
index 8f301a706b3..ad6acffb8c9 100644
--- a/resolv/nss_dns/dns-network.c
+++ b/resolv/nss_dns/dns-network.c
@@ -345,10 +345,23 @@ getanswer_r (const querybuf *answer, int anslen, struct netent *result,
       if (n < 0 || res_dnok (bp) == 0)
 	break;
       cp += n;
+
+      if (end_of_message - cp < 10)
+	{
+	  __set_h_errno (NO_RECOVERY);
+	  return NSS_STATUS_UNAVAIL;
+	}
+
       GETSHORT (type, cp);
       GETSHORT (class, cp);
       cp += INT32SZ;		/* TTL */
-      GETSHORT (n, cp);
+      uint16_t rdatalen;
+      GETSHORT (rdatalen, cp);
+      if (end_of_message - cp < rdatalen)
+	{
+	  __set_h_errno (NO_RECOVERY);
+	  return NSS_STATUS_UNAVAIL;
+	}
 
       if (class == C_IN && type == T_PTR)
 	{
@@ -370,7 +383,7 @@ getanswer_r (const querybuf *answer, int anslen, struct netent *result,
 	      cp += n;
 	      return NSS_STATUS_UNAVAIL;
 	    }
-	  cp += n;
+	  cp += rdatalen;
          if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
            {
              *alias_pointer++ = bp;
@@ -381,6 +394,9 @@ getanswer_r (const querybuf *answer, int anslen, struct netent *result,
              ++have_answer;
            }
 	}
+      else
+	/* Skip over unknown record data.  */
+	cp += rdatalen;
     }
 
   if (have_answer)