[rtems commit] ppp: PR1943: Avoid NULL pointer access

[Gedare Bloom]

Module:    rtems
Branch:    4.10
Commit:    d1d31a5f6114ff73b11cf67bb6a09b3df0d8748c
Changeset: http://git.rtems.org/rtems/commit/?id=d1d31a5f6114ff73b11cf67bb6a09b3df0d8748c

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Wed Oct  8 11:43:10 2014 +0200

ppp: PR1943: Avoid NULL pointer access

Waiting for mbufs at this level is a bad solution.  It would be better
to try to allocate a new mbuf chain before we hand over the current mbuf
chain to the upper layer.  In case the allocation fails we should drop
the current packet and use its mbuf chain for a new packet.

---

 cpukit/libnetworking/net/ppp_tty.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/cpukit/libnetworking/net/ppp_tty.c b/cpukit/libnetworking/net/ppp_tty.c
index 1d91266..9b2ca26 100644
--- a/cpukit/libnetworking/net/ppp_tty.c
+++ b/cpukit/libnetworking/net/ppp_tty.c
@@ -708,14 +708,8 @@ pppallocmbuf(struct ppp_softc *sc, struct mbuf **mp)
     m = *mp;
     if ( m == NULL ) {
       /* get mbuf header */
-      MGETHDR(m, M_DONTWAIT, MT_DATA);
-      if ( m == NULL ) {
-        /* error - set condition to break out */
-        printf("pppallocmbuf: MGETHDR failed\n");
-        break;
-      }
-      MCLGET(m, M_DONTWAIT);
-      m->m_next = NULL;
+      MGETHDR(m, M_WAIT, MT_DATA);
+      MCLGET(m, M_WAIT);
       *mp = m;
     }