Handle out-of-memory case in svc_tcp.c/svc_unix.c:rendezvous_request.

If glibc is build with -O3 on at least 390 (-m31) or x86 (-m32),
gcc 11 dumps this warning:
svc_tcp.c: In function 'rendezvous_request':
svc_tcp.c:274:3: error: 'memcpy' offset [0, 15] is out of the bounds [0, 0] [-Werror=array-bounds]
  274 |   memcpy (&xprt->xp_raddr, &addr, sizeof (addr));
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

In out-of-memory case, if one of the mallocs in makefd_xprt function
returns NULL, a message is dumped, makefd_xprt returns NULL
and the subsequent memcpy would copy to NULL.

Instead of a segfaulting, we delay a bit (see also __svc_accept_failed
and Bug 14889 (CVE-2011-4609) - svc_run() produces high cpu usage when
accept() fails with EMFILE (CVE-2011-4609).

The same applies to svc_unix.c.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

4 files changed, 25 insertions, 2 deletions

diff --git a/include/rpc/svc.h b/include/rpc/svc.h
index 465bf4427d..d9c0e8fbca 100644
--- a/include/rpc/svc.h
+++ b/include/rpc/svc.h
@@ -38,6 +38,7 @@ libc_hidden_proto (svc_getreq_common)
 libc_hidden_proto (svc_getreq_poll)
 
 extern void __svc_accept_failed (void) attribute_hidden;
+extern void __svc_wait_on_error (void) attribute_hidden;
 
 # endif /* !_ISOMAC */
 #endif
diff --git a/sunrpc/svc.c b/sunrpc/svc.c
index 917e9a311c..3ed6cee09e 100644
--- a/sunrpc/svc.c
+++ b/sunrpc/svc.c
@@ -545,6 +545,13 @@ svc_getreq_common (const int fd)
 }
 libc_hidden_nolink_sunrpc (svc_getreq_common, GLIBC_2_2)
 
+void
+__svc_wait_on_error (void)
+{
+  struct timespec ts = { .tv_sec = 0, .tv_nsec = 50000000 };
+  __nanosleep (&ts, NULL);
+}
+
 /* If there are no file descriptors available, then accept will fail.
    We want to delay here so the connection request can be dequeued;
    otherwise we can bounce between polling and accepting, never giving the
@@ -555,8 +562,7 @@ __svc_accept_failed (void)
 {
   if (errno == EMFILE)
     {
-      struct timespec ts = { .tv_sec = 0, .tv_nsec = 50000000 };
-      __nanosleep (&ts, NULL);
+      __svc_wait_on_error ();
     }
 }
 
diff --git a/sunrpc/svc_tcp.c b/sunrpc/svc_tcp.c
index efbdd22548..12de60f605 100644
--- a/sunrpc/svc_tcp.c
+++ b/sunrpc/svc_tcp.c
@@ -271,6 +271,14 @@ again:
    * make a new transporter (re-uses xprt)
    */
   xprt = makefd_xprt (sock, r->sendsize, r->recvsize);
+
+  /* If we are out of memory, makefd_xprt has already dumped an error.  */
+  if (xprt == NULL)
+    {
+      __svc_wait_on_error ();
+      return FALSE;
+    }
+
   memcpy (&xprt->xp_raddr, &addr, sizeof (addr));
   xprt->xp_addrlen = len;
   return FALSE;		/* there is never an rpc msg to be processed */
diff --git a/sunrpc/svc_unix.c b/sunrpc/svc_unix.c
index e01afeabe6..3decea427c 100644
--- a/sunrpc/svc_unix.c
+++ b/sunrpc/svc_unix.c
@@ -270,6 +270,14 @@ again:
   memset (&in_addr, '\0', sizeof (in_addr));
   in_addr.sin_family = AF_UNIX;
   xprt = makefd_xprt (sock, r->sendsize, r->recvsize);
+
+  /* If we are out of memory, makefd_xprt has already dumped an error.  */
+  if (xprt == NULL)
+    {
+      __svc_wait_on_error ();
+      return FALSE;
+    }
+
   memcpy (&xprt->xp_raddr, &in_addr, sizeof (in_addr));
   xprt->xp_addrlen = len;
   return FALSE;		/* there is never an rpc msg to be processed */