[PATCH] Fix unbound stack use in NIS NSS module

[Andreas Schwab <schwab at suse dot de>]

yp_match needs to put its request in a single RPC packet, so don't
bother trying to support big items.

Andreas.

	[BZ #16932]
	* nis/nss_nis/nis-hosts.c (internal_gethostbyname2_r)
	(_nss_nis_gethostbyname4_r): Return error if item length is larger
	than maximum RPC packet size.
	* nis/nss_nis/nis-initgroups.c (initgroups_netid): Likewise.
	* nis/nss_nis/nis-network.c (_nss_nis_getnetbyname_r): Likewise.
	* nis/nss_nis/nis-service.c (_nss_nis_getservbyname_r)
	(_nss_nis_getservbyport_r): Likewise.
---
 nis/nss_nis/nis-hosts.c      | 14 ++++++++++++++
 nis/nss_nis/nis-initgroups.c |  7 +++++++
 nis/nss_nis/nis-network.c    |  7 +++++++
 nis/nss_nis/nis-service.c    | 14 ++++++++++++++
 4 files changed, 42 insertions(+)

diff --git a/nis/nss_nis/nis-hosts.c b/nis/nss_nis/nis-hosts.c
index 462176e..d6192b1 100644
--- a/nis/nss_nis/nis-hosts.c
+++ b/nis/nss_nis/nis-hosts.c
@@ -270,6 +270,13 @@ internal_gethostbyname2_r (const char *name, int af, struct hostent *host,
 
   /* Convert name to lowercase.  */
   size_t namlen = strlen (name);
+  /* Limit name length to the maximum size of an RPC packet.  */
+  if (namlen > UDPMSGSIZE)
+    {
+      *errnop = ERANGE;
+      return NSS_STATUS_UNAVAIL;
+    }
+
   char name2[namlen + 1];
   size_t i;
 
@@ -461,6 +468,13 @@ _nss_nis_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
 
   /* Convert name to lowercase.  */
   size_t namlen = strlen (name);
+  /* Limit name length to the maximum size of an RPC packet.  */
+  if (namlen > UDPMSGSIZE)
+    {
+      *errnop = ERANGE;
+      return NSS_STATUS_UNAVAIL;
+    }
+
   char name2[namlen + 1];
   size_t i;
 
diff --git a/nis/nss_nis/nis-initgroups.c b/nis/nss_nis/nis-initgroups.c
index e8fcca1..9542fae 100644
--- a/nis/nss_nis/nis-initgroups.c
+++ b/nis/nss_nis/nis-initgroups.c
@@ -150,6 +150,13 @@ initgroups_netid (uid_t uid, gid_t group, long int *start, long int *size,
 		  gid_t **groupsp, long int limit, int *errnop,
 		  const char *domainname)
 {
+  /* Limit domainname length to the maximum size of an RPC packet.  */
+  if (strlen (domainname) > UDPMSGSIZE)
+    {
+      *errnop = ERANGE;
+      return NSS_STATUS_UNAVAIL;
+    }
+
   /* Prepare the key.  The form is "unix.UID@DOMAIN" with the UID and
      DOMAIN field filled in appropriately.  */
   char key[sizeof ("unix.@") + sizeof (uid_t) * 3 + strlen (domainname)];
diff --git a/nis/nss_nis/nis-network.c b/nis/nss_nis/nis-network.c
index f28fbda..f1b72bc 100644
--- a/nis/nss_nis/nis-network.c
+++ b/nis/nss_nis/nis-network.c
@@ -179,6 +179,13 @@ _nss_nis_getnetbyname_r (const char *name, struct netent *net, char *buffer,
 
   /* Convert name to lowercase.  */
   size_t namlen = strlen (name);
+  /* Limit name length to the maximum size of an RPC packet.  */
+  if (namlen > UDPMSGSIZE)
+    {
+      *errnop = ERANGE;
+      return NSS_STATUS_UNAVAIL;
+    }
+
   char name2[namlen + 1];
   size_t i;
 
diff --git a/nis/nss_nis/nis-service.c b/nis/nss_nis/nis-service.c
index f9b4a86..44e4e13 100644
--- a/nis/nss_nis/nis-service.c
+++ b/nis/nss_nis/nis-service.c
@@ -271,6 +271,13 @@ _nss_nis_getservbyname_r (const char *name, const char *protocol,
   /* If the protocol is given, we could try if our NIS server knows
      about services.byservicename map. If yes, we only need one query.  */
   size_t keylen = strlen (name) + (protocol ? 1 + strlen (protocol) : 0);
+  /* Limit key length to the maximum size of an RPC packet.  */
+  if (keylen > UDPMSGSIZE)
+    {
+      *errnop = ERANGE;
+      return NSS_STATUS_UNAVAIL;
+    }
+
   char key[keylen + 1];
 
   /* key is: "name/proto" */
@@ -355,6 +362,13 @@ _nss_nis_getservbyport_r (int port, const char *protocol,
      Otherwise try first port/tcp, then port/udp and then fallback
      to sequential scanning of services.byname.  */
   const char *proto = protocol != NULL ? protocol : "tcp";
+  /* Limit protocol name length to the maximum size of an RPC packet.  */
+  if (strlen (proto) > UDPMSGSIZE)
+    {
+      *errnop = ERANGE;
+      return NSS_STATUS_UNAVAIL;
+    }
+
   do
     {
       /* key is: "port/proto" */
-- 
1.9.2

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."