CVE-2016-3075: Stack overflow in _nss_dns_getnetbyname_r [BZ #19879]

The defensive copy is not needed because the name may not alias the
output buffer.

(cherry picked from commit 317b199b4aff8cfa27f2302ab404d2bb5032b9a4)
(cherry picked from commit f5b3338d70a7a2c626331ac4589b6deb2f610432)

diff --git a/ChangeLog b/ChangeLog
index 3652d5f029221eb26f33d8b60479bf807d520f19..4b5cd019e19ce92c38ec58682b16f391582f2e6c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-05-24  Florian Weimer  <fweimer@redhat.com>
+
+       [BZ #19879]
+       CVE-2016-3075
+       * resolv/nss_dns/dns-network.c (_nss_dns_getnetbyname_r): Do not
+       copy name.
+
 2016-05-24  Paul Pluzhnikov  <ppluzhnikov@google.com>
 
        [BZ #17905]

diff --git a/NEWS b/NEWS
index e6a520774aa8effb1113da50fa8bfeb755c8bd09..dc8679f8cac134fa1cf55f8af077e4e3be8f3589 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -17,6 +17,10 @@ Version 2.20.1
   called with the GLOB_ALTDIRFUNC flag and encountered a long file name.
   Reported by Alexander Cherepanov.  (CVE-2016-1234)
 
+* An unnecessary stack copy in _nss_dns_getnetbyname_r was removed.  It
+  could result in a stack overflow when getnetbyname was called with an
+  overly long name.  (CVE-2016-3075)
+
 * Previously, getaddrinfo copied large amounts of address data to the stack,
   even after the fix for CVE-2013-4458 has been applied, potentially
   resulting in a stack overflow.  getaddrinfo now uses a heap allocation

diff --git a/resolv/nss_dns/dns-network.c b/resolv/nss_dns/dns-network.c
index 08cf0a6462ce9bb12ea04507041b5958a1ea24e3..335604adc261b59ad89279f941ec818476af907d 100644 (file)
--- a/resolv/nss_dns/dns-network.c
+++ b/resolv/nss_dns/dns-network.c
@@ -118,17 +118,14 @@ _nss_dns_getnetbyname_r (const char *name, struct netent *result,
   } net_buffer;
   querybuf *orig_net_buffer;
   int anslen;
-  char *qbuf;
   enum nss_status status;
 
   if (__res_maybe_init (&_res, 0) == -1)
     return NSS_STATUS_UNAVAIL;
 
-  qbuf = strdupa (name);
-
   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 
-  anslen = __libc_res_nsearch (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
+  anslen = __libc_res_nsearch (&_res, name, C_IN, T_PTR, net_buffer.buf->buf,
                               1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
   if (anslen < 0)
     {