[glibc/release/2.32/master] CVE-2022-23218: Buffer overflow in sunrpc svcunix_create (bug 28768)

[Dmitry Levin <ldv@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0c9137a4449789649eb42b3f1b7cfdff4968ff2b

commit 0c9137a4449789649eb42b3f1b7cfdff4968ff2b
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Jan 17 11:49:25 2022 +0100

    CVE-2022-23218: Buffer overflow in sunrpc svcunix_create (bug 28768)
    
    The sunrpc function svcunix_create suffers from a stack-based buffer
    overflow with overlong pathname arguments.
    
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    (cherry picked from commit f545ad4928fa1f27a3075265182b38a4f939a5f7)

Diff:
---
 NEWS                  |  4 ++++
 sunrpc/Makefile       |  2 +-
 sunrpc/svc_unix.c     | 11 ++++-------
 sunrpc/tst-bug28768.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/NEWS b/NEWS
index 53ca17db43..0adef96756 100644
--- a/NEWS
+++ b/NEWS
@@ -42,6 +42,9 @@ Security related changes:
   legacy function could result in a stack-based buffer overflow when
   using the "unix" protocol.  Reported by Martin Sebor.
 
+  CVE-2022-23218: Passing an overlong file name to the svcunix_create
+  legacy function could result in a stack-based buffer overflow.
+
 The following bugs are resolved with this release:
 
   [20019] NULL pointer dereference in libc.so.6 IFUNC due to uninitialized GOT
@@ -101,6 +104,7 @@ The following bugs are resolved with this release:
   [28524] Conversion from ISO-2022-JP-3 with iconv may emit spurious NULs
   [28607] Masked signals are delivered on thread exit
   [28755] overflow bug in wcsncmp_avx2 and wcsncmp_evex
+  [28768] CVE-2022-23218: Buffer overflow in sunrpc svcunix_create
   [28896] strncmp-avx2-rtm and wcsncmp-avx2-rtm fallback on non-rtm
     variants when avoiding overflow
   [29304] libc: mq_timedreceive does not handle 64 bit syscall return
diff --git a/sunrpc/Makefile b/sunrpc/Makefile
index cea958608e..0d36071ba4 100644
--- a/sunrpc/Makefile
+++ b/sunrpc/Makefile
@@ -65,7 +65,7 @@ shared-only-routines = $(routines)
 endif
 
 tests = tst-xdrmem tst-xdrmem2 test-rpcent tst-udp-error tst-udp-timeout \
-  tst-udp-nonblocking tst-bug22542
+  tst-udp-nonblocking tst-bug22542 tst-bug28768
 
 xtests := tst-getmyaddr
 
diff --git a/sunrpc/svc_unix.c b/sunrpc/svc_unix.c
index e01afeabe6..b065d6063a 100644
--- a/sunrpc/svc_unix.c
+++ b/sunrpc/svc_unix.c
@@ -154,7 +154,10 @@ svcunix_create (int sock, u_int sendsize, u_int recvsize, char *path)
   SVCXPRT *xprt;
   struct unix_rendezvous *r;
   struct sockaddr_un addr;
-  socklen_t len = sizeof (struct sockaddr_in);
+  socklen_t len = sizeof (addr);
+
+  if (__sockaddr_un_set (&addr, path) < 0)
+    return NULL;
 
   if (sock == RPC_ANYSOCK)
     {
@@ -165,12 +168,6 @@ svcunix_create (int sock, u_int sendsize, u_int recvsize, char *path)
 	}
       madesock = TRUE;
     }
-  memset (&addr, '\0', sizeof (addr));
-  addr.sun_family = AF_UNIX;
-  len = strlen (path) + 1;
-  memcpy (addr.sun_path, path, len);
-  len += sizeof (addr.sun_family);
-
   __bind (sock, (struct sockaddr *) &addr, len);
 
   if (__getsockname (sock, (struct sockaddr *) &addr, &len) != 0
diff --git a/sunrpc/tst-bug28768.c b/sunrpc/tst-bug28768.c
new file mode 100644
index 0000000000..35a4b7b0b3
--- /dev/null
+++ b/sunrpc/tst-bug28768.c
@@ -0,0 +1,42 @@
+/* Test to verify that long path is rejected by svcunix_create (bug 28768).
+   Copyright (C) 2022 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 <errno.h>
+#include <rpc/svc.h>
+#include <shlib-compat.h>
+#include <string.h>
+#include <support/check.h>
+
+/* svcunix_create does not have a default version in linkobj/libc.so.  */
+compat_symbol_reference (libc, svcunix_create, svcunix_create, GLIBC_2_1);
+
+static int
+do_test (void)
+{
+  char pathname[109];
+  memset (pathname, 'x', sizeof (pathname));
+  pathname[sizeof (pathname) - 1] = '\0';
+
+  errno = 0;
+  TEST_VERIFY (svcunix_create (RPC_ANYSOCK, 4096, 4096, pathname) == NULL);
+  TEST_COMPARE (errno, EINVAL);
+
+  return 0;
+}
+
+#include <support/test-driver.c>