ppp: potential NULL dereference in ppp_mp_explode()

Smatch complains because we check whether "pch->chan" is NULL and then
dereference it unconditionally on the next line.  Partly the reason this
bug was introduced is because code was too complicated.  I've simplified
it a little.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 6695a51e09e9..736b91703b3e 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -1314,8 +1314,13 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
         i = 0;
         list_for_each_entry(pch, &ppp->channels, clist) {
-                navail += pch->avail = (pch->chan != NULL);
-                pch->speed = pch->chan->speed;
+                if (pch->chan) {
+                        pch->avail = 1;
+                        navail++;
+                        pch->speed = pch->chan->speed;
+                } else {
+                        pch->avail = 0;
+                }
                 if (pch->avail) {
                         if (skb_queue_empty(&pch->file.xq) ||
                                 !pch->had_frag) {