[Buildroot] [git commit branch/2017.02.x] rpcbind: add upstream security fix for CVE-2017-8779

Peter Korsgaard peter at korsgaard.com
Wed May 17 20:36:19 UTC 2017


commit: https://git.buildroot.net/buildroot/commit/?id=e8a44eb7e5745d094830b1ed8b5cc785fb33a33b
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2017.02.x

CVE-2017-8779: rpcbind through 0.2.4, LIBTIRPC through 1.0.1 and 1.0.2-rc
through 1.0.2-rc3, and NTIRPC through 1.4.3 do not consider the maximum RPC
data size during memory allocation for XDR strings, which allows remote
attackers to cause a denial of service (memory consumption with no
subsequent free) via a crafted UDP packet to port 111, aka rpcbomb.

For more details, see:
https://guidovranken.wordpress.com/2017/05/03/rpcbomb-remote-rpcbind-denial-of-service-patches/

Backport upstream fix to version 0.2.3 and unconditionally include syslog.h
to fix a build issue when RPCBIND_DEBUG is disabled (which it is in
Buildroot).

Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
(cherry picked from commit 954509fb84cfbcf50a2f3020d817a118f7357d3a)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 ...r-all-svc_getargs-calls-with-svc_freeargs.patch | 231 +++++++++++++++++++++
 1 file changed, 231 insertions(+)

diff --git a/package/rpcbind/0004-rpcbind-pair-all-svc_getargs-calls-with-svc_freeargs.patch b/package/rpcbind/0004-rpcbind-pair-all-svc_getargs-calls-with-svc_freeargs.patch
new file mode 100644
index 0000000..130e5d7
--- /dev/null
+++ b/package/rpcbind/0004-rpcbind-pair-all-svc_getargs-calls-with-svc_freeargs.patch
@@ -0,0 +1,231 @@
+From 093bf65c79af417cffa09d6475f58923540eebcc Mon Sep 17 00:00:00 2001
+From: Doran Moppert <dmoppert at redhat.com>
+Date: Thu, 11 May 2017 11:42:54 -0400
+Subject: [PATCH] rpcbind: pair all svc_getargs() calls with svc_freeargs() to
+ avoid memory leak
+
+This patch is to address CVE-2017-8779 "rpcbomb" in rpcbind, discussed
+at [1], [2], [3].  The last link suggests this issue is actually a bug
+in rpcbind, which led me here.
+
+The leak caused by the reproducer at [4] appears to come from
+rpcb_service_4(), in the case where svc_getargs() returns false and the
+function had an early return, rather than passing through the cleanup
+path at done:, as would otherwise occur.
+
+It also addresses a couple of other locations where the same fault seems
+to exist, though I haven't been able to exercise those.  I hope someone
+more intimate with rpc(3) can confirm my understanding is correct, and
+that I haven't introduced any new bugs.
+
+Without this patch, using the reproducer (and variants) repeatedly
+against rpcbind with a numBytes argument of 1_000_000_000, /proc/$(pidof
+rpcbind)/status reports VmSize increase of 976564 kB each call, and
+VmRSS increase of around 260 kB every 33 calls - the specific numbers
+are probably an artifact of my rhel/glibc version.  With the patch,
+there is a small (~50 kB) VmSize increase with the first message, but
+thereafter both VmSize and VmRSS remain steady.
+
+[1]: http://seclists.org/oss-sec/2017/q2/209
+[2]: https://bugzilla.redhat.com/show_bug.cgi?id=1448124
+[3]: https://sourceware.org/ml/libc-alpha/2017-05/msg00129.html
+[4]: https://github.com/guidovranken/rpcbomb/
+
+Signed-off-by: Doran Moppert <dmoppert at redhat.com>
+Signed-off-by: Steve Dickson <steved at redhat.com>
+(cherry picked from commit 7ea36eeece56b59f98e469934e4c20b4da043346)
+[Peter: unconditionally include syslog.h for LOG_DEBUG]
+Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
+---
+ src/pmap_svc.c     | 58 ++++++++++++++++++++++++++++++++++++++++++++----------
+ src/rpcb_svc.c     |  2 +-
+ src/rpcb_svc_4.c   |  2 +-
+ src/rpcb_svc_com.c |  8 ++++++++
+ 4 files changed, 58 insertions(+), 12 deletions(-)
+
+diff --git a/src/pmap_svc.c b/src/pmap_svc.c
+index ad28b93..f730bed 100644
+--- a/src/pmap_svc.c
++++ b/src/pmap_svc.c
+@@ -53,8 +53,8 @@ static	char sccsid[] = "@(#)pmap_svc.c 1.23 89/04/05 Copyr 1984 Sun Micro";
+ #include <rpc/rpc.h>
+ #include <rpc/pmap_prot.h>
+ #include <rpc/rpcb_prot.h>
+-#ifdef RPCBIND_DEBUG
+ #include <syslog.h>
++#ifdef RPCBIND_DEBUG
+ #include <stdlib.h>
+ #endif
+ #include "rpcbind.h"
+@@ -175,6 +175,7 @@ pmapproc_change(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt, unsigned long
+ 	long ans;
+ 	uid_t uid;
+ 	char uidbuf[32];
++	int rc = TRUE;
+ 
+ 	/*
+ 	 * Can't use getpwnam here. We might end up calling ourselves
+@@ -194,7 +195,8 @@ pmapproc_change(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt, unsigned long
+ 
+ 	if (!svc_getargs(xprt, (xdrproc_t) xdr_pmap, (char *)&reg)) {
+ 		svcerr_decode(xprt);
+-		return (FALSE);
++		rc = FALSE;
++		goto done;
+ 	}
+ #ifdef RPCBIND_DEBUG
+ 	if (debugging)
+@@ -205,7 +207,8 @@ pmapproc_change(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt, unsigned long
+ 
+ 	if (!check_access(xprt, op, reg.pm_prog, PMAPVERS)) {
+ 		svcerr_weakauth(xprt);
+-		return (FALSE);
++		rc = (FALSE);
++		goto done;
+ 	}
+ 
+ 	rpcbreg.r_prog = reg.pm_prog;
+@@ -258,7 +261,16 @@ done_change:
+ 		rpcbs_set(RPCBVERS_2_STAT, ans);
+ 	else
+ 		rpcbs_unset(RPCBVERS_2_STAT, ans);
+-	return (TRUE);
++done:
++	if (!svc_freeargs(xprt, (xdrproc_t) xdr_pmap, (char *)&reg)) {
++		if (debugging) {
++			(void) xlog(LOG_DEBUG, "unable to free arguments\n");
++			if (doabort) {
++				rpcbind_abort();
++			}
++		}
++	}
++	return (rc);
+ }
+ 
+ /* ARGSUSED */
+@@ -272,15 +284,18 @@ pmapproc_getport(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
+ #ifdef RPCBIND_DEBUG
+ 	char *uaddr;
+ #endif
++	int rc = TRUE;
+ 
+ 	if (!svc_getargs(xprt, (xdrproc_t) xdr_pmap, (char *)&reg)) {
+ 		svcerr_decode(xprt);
+-		return (FALSE);
++		rc = FALSE;
++		goto done;
+ 	}
+ 
+ 	if (!check_access(xprt, PMAPPROC_GETPORT, reg.pm_prog, PMAPVERS)) {
+ 		svcerr_weakauth(xprt);
+-		return FALSE;
++		rc = FALSE;
++		goto done;
+ 	}
+ 
+ #ifdef RPCBIND_DEBUG
+@@ -330,21 +345,34 @@ pmapproc_getport(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
+ 		pmap_ipprot2netid(reg.pm_prot) ?: "<unknown>",
+ 		port ? udptrans : "");
+ 
+-	return (TRUE);
++done:
++	if (!svc_freeargs(xprt, (xdrproc_t) xdr_pmap, (char *)&reg)) {
++		if (debugging) {
++			(void) xlog(LOG_DEBUG, "unable to free arguments\n");
++			if (doabort) {
++				rpcbind_abort();
++			}
++		}
++	}
++	return (rc);
+ }
+ 
+ /* ARGSUSED */
+ static bool_t
+ pmapproc_dump(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
+ {
++	int rc = TRUE;
++
+ 	if (!svc_getargs(xprt, (xdrproc_t)xdr_void, NULL)) {
+ 		svcerr_decode(xprt);
+-		return (FALSE);
++		rc = FALSE;
++		goto done;
+ 	}
+ 
+ 	if (!check_access(xprt, PMAPPROC_DUMP, 0, PMAPVERS)) {
+ 		svcerr_weakauth(xprt);
+-		return FALSE;
++		rc = FALSE;
++		goto done;
+ 	}
+ 	
+ 	if ((!svc_sendreply(xprt, (xdrproc_t) xdr_pmaplist_ptr,
+@@ -354,7 +382,17 @@ pmapproc_dump(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
+ 			rpcbind_abort();
+ 		}
+ 	}
+-	return (TRUE);
++
++done:
++	if (!svc_freeargs(xprt, (xdrproc_t) xdr_pmap, (char *)NULL)) {
++		if (debugging) {
++			(void) xlog(LOG_DEBUG, "unable to free arguments\n");
++			if (doabort) {
++				rpcbind_abort();
++			}
++		}
++	}
++	return (rc);
+ }
+ 
+ int pmap_netid2ipprot(const char *netid)
+diff --git a/src/rpcb_svc.c b/src/rpcb_svc.c
+index bd92201..0c22a9d 100644
+--- a/src/rpcb_svc.c
++++ b/src/rpcb_svc.c
+@@ -166,7 +166,7 @@ rpcb_service_3(struct svc_req *rqstp, SVCXPRT *transp)
+ 		svcerr_decode(transp);
+ 		if (debugging)
+ 			(void) xlog(LOG_DEBUG, "rpcbind: could not decode");
+-		return;
++		goto done;
+ 	}
+ 
+ 	if (rqstp->rq_proc == RPCBPROC_SET
+diff --git a/src/rpcb_svc_4.c b/src/rpcb_svc_4.c
+index b673452..3e37b54 100644
+--- a/src/rpcb_svc_4.c
++++ b/src/rpcb_svc_4.c
+@@ -220,7 +220,7 @@ rpcb_service_4(struct svc_req *rqstp, SVCXPRT *transp)
+ 		svcerr_decode(transp);
+ 		if (debugging)
+ 			(void) xlog(LOG_DEBUG, "rpcbind: could not decode\n");
+-		return;
++		goto done;
+ 	}
+ 
+ 	if (rqstp->rq_proc == RPCBPROC_SET
+diff --git a/src/rpcb_svc_com.c b/src/rpcb_svc_com.c
+index ff9ce6b..98ede61 100644
+--- a/src/rpcb_svc_com.c
++++ b/src/rpcb_svc_com.c
+@@ -931,6 +931,14 @@ error:
+ 	if (call_msg.rm_xid != 0)
+ 		(void) free_slot_by_xid(call_msg.rm_xid);
+ out:
++	if (!svc_freeargs(transp, (xdrproc_t) xdr_rmtcall_args, (char *) &a)) {
++		if (debugging) {
++			(void) xlog(LOG_DEBUG, "unable to free arguments\n");
++			if (doabort) {
++				rpcbind_abort();
++			}
++		}
++	}
+ 	if (local_uaddr)
+ 		free(local_uaddr);
+ 	if (buf_alloc)
+-- 
+2.11.0
+


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