rpcbind: add upstream security fix for CVE-2017-8779
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@korsgaard.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
This commit is contained in:
Peter Korsgaard
Thomas Petazzoni
parent
1dd696ffe2
commit
954509fb84
@ -0,0 +1,231 @@
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From 093bf65c79af417cffa09d6475f58923540eebcc Mon Sep 17 00:00:00 2001
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From: Doran Moppert <dmoppert@redhat.com>
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Date: Thu, 11 May 2017 11:42:54 -0400
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Subject: [PATCH] rpcbind: pair all svc_getargs() calls with svc_freeargs() to
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avoid memory leak
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This patch is to address CVE-2017-8779 "rpcbomb" in rpcbind, discussed
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at [1], [2], [3]. The last link suggests this issue is actually a bug
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in rpcbind, which led me here.
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The leak caused by the reproducer at [4] appears to come from
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rpcb_service_4(), in the case where svc_getargs() returns false and the
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function had an early return, rather than passing through the cleanup
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path at done:, as would otherwise occur.
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It also addresses a couple of other locations where the same fault seems
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to exist, though I haven't been able to exercise those. I hope someone
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more intimate with rpc(3) can confirm my understanding is correct, and
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that I haven't introduced any new bugs.
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Without this patch, using the reproducer (and variants) repeatedly
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against rpcbind with a numBytes argument of 1_000_000_000, /proc/$(pidof
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rpcbind)/status reports VmSize increase of 976564 kB each call, and
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VmRSS increase of around 260 kB every 33 calls - the specific numbers
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are probably an artifact of my rhel/glibc version. With the patch,
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there is a small (~50 kB) VmSize increase with the first message, but
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thereafter both VmSize and VmRSS remain steady.
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[1]: http://seclists.org/oss-sec/2017/q2/209
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[2]: https://bugzilla.redhat.com/show_bug.cgi?id=1448124
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[3]: https://sourceware.org/ml/libc-alpha/2017-05/msg00129.html
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[4]: https://github.com/guidovranken/rpcbomb/
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Signed-off-by: Doran Moppert <dmoppert@redhat.com>
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Signed-off-by: Steve Dickson <steved@redhat.com>
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(cherry picked from commit 7ea36eeece56b59f98e469934e4c20b4da043346)
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[Peter: unconditionally include syslog.h for LOG_DEBUG]
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Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
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---
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src/pmap_svc.c | 58 ++++++++++++++++++++++++++++++++++++++++++++----------
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src/rpcb_svc.c | 2 +-
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src/rpcb_svc_4.c | 2 +-
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src/rpcb_svc_com.c | 8 ++++++++
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4 files changed, 58 insertions(+), 12 deletions(-)
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diff --git a/src/pmap_svc.c b/src/pmap_svc.c
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index ad28b93..f730bed 100644
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--- a/src/pmap_svc.c
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+++ b/src/pmap_svc.c
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@@ -53,8 +53,8 @@ static char sccsid[] = "@(#)pmap_svc.c 1.23 89/04/05 Copyr 1984 Sun Micro";
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#include <rpc/rpc.h>
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#include <rpc/pmap_prot.h>
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#include <rpc/rpcb_prot.h>
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-#ifdef RPCBIND_DEBUG
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#include <syslog.h>
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+#ifdef RPCBIND_DEBUG
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#include <stdlib.h>
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#endif
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#include "rpcbind.h"
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@@ -175,6 +175,7 @@ pmapproc_change(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt, unsigned long
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long ans;
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uid_t uid;
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char uidbuf[32];
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+ int rc = TRUE;
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/*
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* Can't use getpwnam here. We might end up calling ourselves
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@@ -194,7 +195,8 @@ pmapproc_change(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt, unsigned long
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if (!svc_getargs(xprt, (xdrproc_t) xdr_pmap, (char *)®)) {
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svcerr_decode(xprt);
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- return (FALSE);
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+ rc = FALSE;
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+ goto done;
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}
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#ifdef RPCBIND_DEBUG
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if (debugging)
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@@ -205,7 +207,8 @@ pmapproc_change(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt, unsigned long
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if (!check_access(xprt, op, reg.pm_prog, PMAPVERS)) {
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svcerr_weakauth(xprt);
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- return (FALSE);
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+ rc = (FALSE);
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+ goto done;
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}
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rpcbreg.r_prog = reg.pm_prog;
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@@ -258,7 +261,16 @@ done_change:
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rpcbs_set(RPCBVERS_2_STAT, ans);
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else
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rpcbs_unset(RPCBVERS_2_STAT, ans);
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- return (TRUE);
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+done:
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+ if (!svc_freeargs(xprt, (xdrproc_t) xdr_pmap, (char *)®)) {
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+ if (debugging) {
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+ (void) xlog(LOG_DEBUG, "unable to free arguments\n");
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+ if (doabort) {
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+ rpcbind_abort();
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+ }
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+ }
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+ }
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+ return (rc);
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}
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/* ARGSUSED */
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@@ -272,15 +284,18 @@ pmapproc_getport(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
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#ifdef RPCBIND_DEBUG
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char *uaddr;
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#endif
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+ int rc = TRUE;
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if (!svc_getargs(xprt, (xdrproc_t) xdr_pmap, (char *)®)) {
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svcerr_decode(xprt);
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- return (FALSE);
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+ rc = FALSE;
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+ goto done;
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}
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if (!check_access(xprt, PMAPPROC_GETPORT, reg.pm_prog, PMAPVERS)) {
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svcerr_weakauth(xprt);
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- return FALSE;
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+ rc = FALSE;
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+ goto done;
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}
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#ifdef RPCBIND_DEBUG
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@@ -330,21 +345,34 @@ pmapproc_getport(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
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pmap_ipprot2netid(reg.pm_prot) ?: "<unknown>",
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port ? udptrans : "");
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- return (TRUE);
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+done:
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+ if (!svc_freeargs(xprt, (xdrproc_t) xdr_pmap, (char *)®)) {
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+ if (debugging) {
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+ (void) xlog(LOG_DEBUG, "unable to free arguments\n");
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+ if (doabort) {
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+ rpcbind_abort();
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+ }
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+ }
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+ }
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+ return (rc);
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}
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/* ARGSUSED */
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static bool_t
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pmapproc_dump(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
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{
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+ int rc = TRUE;
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+
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if (!svc_getargs(xprt, (xdrproc_t)xdr_void, NULL)) {
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svcerr_decode(xprt);
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- return (FALSE);
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+ rc = FALSE;
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+ goto done;
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}
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if (!check_access(xprt, PMAPPROC_DUMP, 0, PMAPVERS)) {
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svcerr_weakauth(xprt);
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- return FALSE;
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+ rc = FALSE;
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+ goto done;
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}
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if ((!svc_sendreply(xprt, (xdrproc_t) xdr_pmaplist_ptr,
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@@ -354,7 +382,17 @@ pmapproc_dump(struct svc_req *rqstp /*__unused*/, SVCXPRT *xprt)
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rpcbind_abort();
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}
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}
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- return (TRUE);
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+
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+done:
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+ if (!svc_freeargs(xprt, (xdrproc_t) xdr_pmap, (char *)NULL)) {
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+ if (debugging) {
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+ (void) xlog(LOG_DEBUG, "unable to free arguments\n");
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+ if (doabort) {
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+ rpcbind_abort();
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+ }
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+ }
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+ }
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+ return (rc);
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}
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int pmap_netid2ipprot(const char *netid)
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diff --git a/src/rpcb_svc.c b/src/rpcb_svc.c
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index bd92201..0c22a9d 100644
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--- a/src/rpcb_svc.c
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+++ b/src/rpcb_svc.c
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@@ -166,7 +166,7 @@ rpcb_service_3(struct svc_req *rqstp, SVCXPRT *transp)
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svcerr_decode(transp);
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if (debugging)
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(void) xlog(LOG_DEBUG, "rpcbind: could not decode");
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- return;
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+ goto done;
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}
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if (rqstp->rq_proc == RPCBPROC_SET
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diff --git a/src/rpcb_svc_4.c b/src/rpcb_svc_4.c
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index b673452..3e37b54 100644
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--- a/src/rpcb_svc_4.c
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+++ b/src/rpcb_svc_4.c
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@@ -220,7 +220,7 @@ rpcb_service_4(struct svc_req *rqstp, SVCXPRT *transp)
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svcerr_decode(transp);
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if (debugging)
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(void) xlog(LOG_DEBUG, "rpcbind: could not decode\n");
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- return;
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+ goto done;
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}
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if (rqstp->rq_proc == RPCBPROC_SET
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diff --git a/src/rpcb_svc_com.c b/src/rpcb_svc_com.c
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index ff9ce6b..98ede61 100644
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--- a/src/rpcb_svc_com.c
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+++ b/src/rpcb_svc_com.c
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@@ -931,6 +931,14 @@ error:
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if (call_msg.rm_xid != 0)
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(void) free_slot_by_xid(call_msg.rm_xid);
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out:
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+ if (!svc_freeargs(transp, (xdrproc_t) xdr_rmtcall_args, (char *) &a)) {
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+ if (debugging) {
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+ (void) xlog(LOG_DEBUG, "unable to free arguments\n");
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+ if (doabort) {
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+ rpcbind_abort();
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+ }
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+ }
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+ }
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if (local_uaddr)
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free(local_uaddr);
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if (buf_alloc)
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--
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2.11.0
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