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authorArjun Shankar <arjun.is@lostca.se>2015-04-21 14:06:31 +0200
committerAurelien Jarno <aurelien@aurel32.net>2015-08-28 22:54:02 +0200
commit126e13008672dddfc757f7260cb8d6ff7c77a4b5 (patch)
tree90e72a6e59192181a0daaf122ef235ac8cc4a8c2
parent323e41a8d8168dac0338bf95c12a8de5b0dfc56e (diff)
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CVE-2015-1781: resolv/nss_dns/dns-host.c buffer overflow [BZ#18287]
(cherry picked from commit 2959eda9272a033863c271aff62095abd01bd4e3)
-rw-r--r--ChangeLog6
-rw-r--r--NEWS10
-rw-r--r--resolv/nss_dns/dns-host.c3
3 files changed, 17 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog
index b88cd041d3..0eb6c3f0a1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-04-21  Arjun Shankar  <arjun.is@lostca.se>
+
+	[BZ #18287]
+	* resolv/nss_dns/dns-host.c (getanswer_r): Adjust buffer length
+	based on padding.  (CVE-2015-1781)
+
 2014-12-11  Andreas Schwab  <schwab@suse.de>
 
 	[BZ #16657]
diff --git a/NEWS b/NEWS
index 6f240cd5e7..7f9388fec9 100644
--- a/NEWS
+++ b/NEWS
@@ -10,7 +10,15 @@ Version 2.19.1
 * The following bugs are resolved with this release:
 
   15946, 16545, 16574, 16623, 16657, 16695, 16878, 16882, 16885, 16916,
-  16932, 16943, 16958, 17048, 17069, 17137, 17213, 17263, 17325, 17555.
+  16932, 16943, 16958, 17048, 17069, 17137, 17213, 17263, 17325, 17555,
+  18287.
+
+* A buffer overflow in gethostbyname_r and related functions performing DNS
+  requests has been fixed.  If the NSS functions were called with a
+  misaligned buffer, the buffer length change due to pointer alignment was
+  not taken into account.  This could result in application crashes or,
+  potentially arbitrary code execution, using crafted, but syntactically
+  valid DNS responses.  (CVE-2015-1781)
 
 * Reverted change of ABI data structures for s390 and s390x:
   On s390 and s390x the size of struct ucontext and jmp_buf was increased in
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index f0b4b17b06..f36d28bd70 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -615,7 +615,8 @@ getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
   int have_to_map = 0;
   uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
   buffer += pad;
-  if (__builtin_expect (buflen < sizeof (struct host_data) + pad, 0))
+  buflen = buflen > pad ? buflen - pad : 0;
+  if (__builtin_expect (buflen < sizeof (struct host_data), 0))
     {
       /* The buffer is too small.  */
     too_small: