GNU C Library master sources branch gentoo/2.23 updated. glibc-2.23-42-g5a7f88f

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       via  5a7f88f0858b67a00c631850a71d7c320ca773ab (commit)
      from  e4acddbc00a49dd3451a1b10635d35eb7c64b474 (commit)

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=5a7f88f0858b67a00c631850a71d7c320ca773ab

commit 5a7f88f0858b67a00c631850a71d7c320ca773ab
Author: Florian Weimer <fweimer@redhat.com>
Date:   Wed Apr 27 15:11:41 2016 +0200

    nss_dns: Validate RDATA length against packet length [BZ #19830]
    
    In _nss_dns_getcanonname_r, a check for the availability of RR metadata
    was missing as well.
    
    (cherry picked from commit f749498fa53df9ead81e291cd9378d67483c2452)
    (cherry picked from commit f233c608d11434aa4a802ded6acdcac1f092729f)

diff --git a/resolv/nss_dns/dns-canon.c b/resolv/nss_dns/dns-canon.c
index fd73f19..072104f 100644
--- a/resolv/nss_dns/dns-canon.c
+++ b/resolv/nss_dns/dns-canon.c
@@ -103,6 +103,11 @@ _nss_dns_getcanonname_r (const char *name, char *buffer, size_t buflen,
 
 	      ptr += s;
 
+	      /* Check that there are enough bytes for the RR
+		 metadata.  */
+	      if (endptr - ptr < 10)
+		goto unavail;
+
 	      /* Check whether type and class match.  */
 	      uint_fast16_t type;
 	      NS_GET16 (type, ptr);
@@ -137,11 +142,16 @@ _nss_dns_getcanonname_r (const char *name, char *buffer, size_t buflen,
 	      if (__ns_get16 (ptr) != ns_c_in)
 		goto unavail;
 
-	      /* Also skip over the TTL.  */
+	      /* Also skip over class and TTL.  */
 	      ptr += sizeof (uint16_t) + sizeof (uint32_t);
 
-	      /* Skip over the data length and data.  */
-	      ptr += sizeof (uint16_t) + __ns_get16 (ptr);
+	      /* Skip over RDATA length and RDATA itself.  */
+	      uint16_t rdatalen = __ns_get16 (ptr);
+	      ptr += sizeof (uint16_t);
+	      /* Not enough room for RDATA.  */
+	      if (endptr - ptr < rdatalen)
+		goto unavail;
+	      ptr += rdatalen;
 	    }
 	}
 
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index 8599f4c..4bb0e62 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -751,6 +751,14 @@ getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
       cp += INT32SZ;			/* TTL */
       n = __ns_get16 (cp);
       cp += INT16SZ;			/* len */
+
+      if (end_of_message - cp < n)
+	{
+	  /* RDATA extends beyond the end of the packet.  */
+	  ++had_error;
+	  continue;
+	}
+
       if (__glibc_unlikely (class != C_IN))
 	{
 	  /* XXX - debug? syslog? */
@@ -1077,6 +1085,13 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname,
       n = __ns_get16 (cp);
       cp += INT16SZ;			/* len */
 
+      if (end_of_message - cp < n)
+	{
+	  /* RDATA extends beyond the end of the packet.  */
+	  ++had_error;
+	  continue;
+	}
+
       if (class != C_IN)
 	{
 	  cp += n;

-----------------------------------------------------------------------

Summary of changes:
 resolv/nss_dns/dns-canon.c |   16 +++++++++++++---
 resolv/nss_dns/dns-host.c  |   15 +++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)


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