[glibc/release/2.33/master] CVE-2022-23219: Buffer overflow in sunrpc clnt_create for "unix" (bug 22542)

[glibc/release/2.33/master] CVE-2022-23219: Buffer overflow in sunrpc clnt_create for "unix" (bug 22542)

[Aurelien Jarno]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4653cd9e3669ff0a49908397e6f2a2eb8e572fdf

commit 4653cd9e3669ff0a49908397e6f2a2eb8e572fdf
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Jan 17 10:21:34 2022 +0100

    CVE-2022-23219: Buffer overflow in sunrpc clnt_create for "unix" (bug 22542)
    
    Processing an overlong pathname in the sunrpc clnt_create function
    results in a stack-based buffer overflow.
    
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    (cherry picked from commit 226b46770c82899b555986583294b049c6ec9b40)

Diff:
---
 NEWS              |  5 +++++
 sunrpc/clnt_gen.c | 10 +++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/NEWS b/NEWS
index 6e4221ca86..71bc4932a0 100644
--- a/NEWS
+++ b/NEWS
@@ -19,10 +19,15 @@ Security related changes:
   issue when using a notification type of SIGEV_THREAD and a thread
   attribute with a non-default affinity mask.
 
+  CVE-2022-23219: Passing an overlong file name to the clnt_create
+  legacy function could result in a stack-based buffer overflow when
+  using the "unix" protocol.  Reported by Martin Sebor.
+
 The following bugs are resolved with this release:
 
   [15271] dlfcn function failure after dlmopen terminates process
   [18435] pthread_once hangs when init routine throws an exception
+  [22542] CVE-2022-23219: Buffer overflow in sunrpc clnt_create for "unix"
   [23462] Static binary with dynamic string tokens ($LIB, $PLATFORM, $ORIGIN)
     crashes
   [27304] pthread_cond_destroy does not pass private flag to futex system calls
diff --git a/sunrpc/clnt_gen.c b/sunrpc/clnt_gen.c
index 13ced8994e..b44357cd88 100644
--- a/sunrpc/clnt_gen.c
+++ b/sunrpc/clnt_gen.c
@@ -57,9 +57,13 @@ clnt_create (const char *hostname, u_long prog, u_long vers,
 
   if (strcmp (proto, "unix") == 0)
     {
-      memset ((char *)&sun, 0, sizeof (sun));
-      sun.sun_family = AF_UNIX;
-      strcpy (sun.sun_path, hostname);
+      if (__sockaddr_un_set (&sun, hostname) < 0)
+	{
+	  struct rpc_createerr *ce = &get_rpc_createerr ();
+	  ce->cf_stat = RPC_SYSTEMERROR;
+	  ce->cf_error.re_errno = errno;
+	  return NULL;
+	}
       sock = RPC_ANYSOCK;
       client = clntunix_create (&sun, prog, vers, &sock, 0, 0);
       if (client == NULL)