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>

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 6695a51..736b917 100644 (file)
--- 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) {