[PATCH] sunrpc: xdr_bytes/xdr_string need to free buffer on error [BZ #21461]
From: Florian Weimer <fweimer at redhat dot com>
To: libc-alpha at sourceware dot org
Date: Mon, 8 May 2017 10:15:18 +0200
The attached patch adds the CVE name and uses a more obvious condition (I think) for the allocation check in xdr_bytes/xdr_string.
Any comments?
Thanks,
Florian
CVE-2017-8804: xdr_bytes/xdr_string need to free buffer on error [BZ #21461]
2017-05-08 Florian Weimer <fweimer@redhat.com>
[BZ #21461]
CVE-2017-8804
* sunrpc/xdr.c (xdr_bytes): Deallocate allocated buffer on error.
(xdr_string): Likewise.
* sunrpc/Makefile (tests): Add tst-xdrmem3.
(tests-special): Add mtrace-tst-xdrmem3.out.
(generated): Add mtrace-tst-xdrmem3.out, tst-xdrmem3.mtrace.
(tst-xdrmem3-ENV): Set MALLOC_TRACE.
(mtrace-tst-xdrmem3.out): Run mtrace.
(tst-xdrmem3): Link against full libc.
* sunrpc/tst-xdrmem3.c: New file.
#diff --git a/NEWS b/NEWS
#index 5558ca3..9960aea 100644
#--- a/NEWS
#+++ b/NEWS
#@@ -62,6 +62,10 @@ Security related changes:
# * The DNS stub resolver limits the advertised UDP buffer size to 1200 bytes,
# to avoid fragmentation-based spoofing attacks.
#
#+* The xdr_bytes and xdr_string routines free the internally allocated
#+ buffer if deserialization of the buffer contents fails for any reason.
#+ (CVE-2017-8804)
#+
# The following bugs are resolved with this release:
#
# [The release manager will add the list generated by
#
diff -Nurp glibc-2.22.orig/sunrpc/Makefile glibc-2.22/sunrpc/Makefile
--- glibc-2.22.orig/sunrpc/Makefile 2015-08-05 09:42:21.000000000 +0300
+++ glibc-2.22/sunrpc/Makefile 2017-06-24 16:25:07.943976935 +0300
@@ -96,9 +96,16 @@ rpcgen-objs = rpc_main.o rpc_hout.o rpc_
extra-objs = $(rpcgen-objs) $(addprefix cross-,$(rpcgen-objs))
others += rpcgen
-tests = tst-xdrmem tst-xdrmem2 test-rpcent
+tests = tst-xdrmem tst-xdrmem2 test-rpcent tst-xdrmem3
xtests := tst-getmyaddr
+tests-special += $(objpfx)mtrace-tst-xdrmem3.out
+generated += mtrace-tst-xdrmem3.out tst-xdrmem3.mtrace
+tst-xdrmem3-ENV = MALLOC_TRACE=$(objpfx)tst-xdrmem3.mtrace
+$(objpfx)mtrace-tst-xdrmem3.out: $(objpfx)tst-xdrmem3.out
+ $(common-objpfx)malloc/mtrace $(objpfx)tst-xdrmem3.mtrace > $@; \
+ $(evaluate-test)
+
ifeq ($(have-thread-library),yes)
xtests += thrsvc
endif
@@ -153,6 +160,7 @@ BUILD_CPPFLAGS += $(sunrpc-CPPFLAGS)
$(objpfx)tst-getmyaddr: $(common-objpfx)linkobj/libc.so
$(objpfx)tst-xdrmem: $(common-objpfx)linkobj/libc.so
$(objpfx)tst-xdrmem2: $(common-objpfx)linkobj/libc.so
+$(objpfx)tst-xdrmem3: $(common-objpfx)linkobj/libc.so
$(objpfx)rpcgen: $(addprefix $(objpfx),$(rpcgen-objs))
diff -Nurp glibc-2.22.orig/sunrpc/tst-xdrmem3.c glibc-2.22/sunrpc/tst-xdrmem3.c
--- glibc-2.22.orig/sunrpc/tst-xdrmem3.c 1970-01-01 02:00:00.000000000 +0200
+++ glibc-2.22/sunrpc/tst-xdrmem3.c 2017-06-24 16:20:53.474180282 +0300
@@ -0,0 +1,83 @@
+/* Test xdr_bytes, xdr_string behavior on deserialization failure.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <mcheck.h>
+#include <rpc/rpc.h>
+#include <support/check.h>
+#include <support/support.h>
+
+static int
+do_test (void)
+{
+ mtrace ();
+
+ /* If do_own_buffer, allocate the buffer and pass it to the
+ deserialization routine. Otherwise the routine is requested to
+ allocate the buffer. */
+ for (int do_own_buffer = 0; do_own_buffer < 2; ++do_own_buffer)
+ {
+ /* Length 16 MiB, but only 2 bytes of data in the packet. */
+ unsigned char buf[] = "\x01\x00\x00\x00\xff";
+ XDR xdrs;
+ char *result;
+ unsigned int result_len;
+
+ /* Test xdr_bytes. */
+ xdrmem_create (&xdrs, (char *) buf, sizeof (buf), XDR_DECODE);
+ result_len = 0;
+ if (do_own_buffer)
+ {
+ char *own_buffer = xmalloc (10);
+ result = own_buffer;
+ TEST_VERIFY (!xdr_bytes (&xdrs, &result, &result_len, 10));
+ TEST_VERIFY (result == own_buffer);
+ free (own_buffer);
+ }
+ else
+ {
+ result = NULL;
+ TEST_VERIFY (!xdr_bytes (&xdrs, &result, &result_len, -1));
+ TEST_VERIFY (result == NULL);
+ }
+ TEST_VERIFY (result_len == 16 * 1024 * 1024);
+ xdr_destroy (&xdrs);
+
+ /* Test xdr_string. */
+ xdrmem_create (&xdrs, (char *) buf, sizeof (buf), XDR_DECODE);
+ if (do_own_buffer)
+ {
+ char *own_buffer = xmalloc (10);
+ result = own_buffer;
+ TEST_VERIFY (!xdr_string (&xdrs, &result, 10));
+ TEST_VERIFY (result == own_buffer);
+ free (own_buffer);
+ }
+ else
+ {
+ result = NULL;
+ TEST_VERIFY (!xdr_string (&xdrs, &result, -1));
+ TEST_VERIFY (result == NULL);
+ }
+ xdr_destroy (&xdrs);
+ }
+
+ return 0;
+}
+
+#include <support/test-driver.c>
+
diff -Nurp glibc-2.22.orig/sunrpc/xdr.c glibc-2.22/sunrpc/xdr.c
--- glibc-2.22.orig/sunrpc/xdr.c 2015-08-05 09:42:21.000000000 +0300
+++ glibc-2.22/sunrpc/xdr.c 2017-06-24 16:20:53.474180282 +0300
@@ -624,14 +624,23 @@ xdr_bytes (xdrs, cpp, sizep, maxsize)
}
if (sp == NULL)
{
- *cpp = sp = (char *) mem_alloc (nodesize);
+ sp = (char *) mem_alloc (nodesize);
+ if (sp == NULL)
+ {
+ (void) __fxprintf (NULL, "%s: %s", __func__,
+ _("out of memory\n"));
+ return FALSE;
+ }
}
- if (sp == NULL)
+ if (!xdr_opaque (xdrs, sp, nodesize))
{
- (void) __fxprintf (NULL, "%s: %s", __func__, _("out of memory\n"));
+ if (*cpp == NULL)
+ /* Deallocate the buffer allocated by this function. */
+ free (sp);
return FALSE;
}
- /* fall into ... */
+ *cpp = sp;
+ return TRUE;
case XDR_ENCODE:
return xdr_opaque (xdrs, sp, nodesize);
@@ -787,14 +796,26 @@ xdr_string (xdrs, cpp, maxsize)
{
case XDR_DECODE:
if (sp == NULL)
- *cpp = sp = (char *) mem_alloc (nodesize);
- if (sp == NULL)
{
- (void) __fxprintf (NULL, "%s: %s", __func__, _("out of memory\n"));
- return FALSE;
+ sp = (char *) mem_alloc (nodesize);
+ if (sp == NULL)
+ {
+ (void) __fxprintf (NULL, "%s: %s", __func__,
+ _("out of memory\n"));
+ return FALSE;
+ }
}
sp[size] = 0;
- /* fall into ... */
+
+ if (!xdr_opaque (xdrs, sp, size))
+ {
+ if (*cpp == NULL)
+ /* Deallocate the buffer allocated by this function. */
+ free (sp);
+ return FALSE;
+ }
+ *cpp = sp;
+ return TRUE;
case XDR_ENCODE:
return xdr_opaque (xdrs, sp, size);
