x25: Patch to fix bug 15678 - x25 accesses fields beyond end of packet.
Here is a patch to stop X.25 examining fields beyond the end of the packet.
For example, when a simple CALL ACCEPTED was received:
10 10 0f
x25_parse_facilities was attempting to decode the FACILITIES field, but this
packet contains no facilities field.
Signed-off-by: John Hughes <john@calva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c
index a21f664..a2765c6 100644
--- a/net/x25/x25_facilities.c
+++ b/net/x25/x25_facilities.c
@@ -35,7 +35,7 @@
struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
{
unsigned char *p = skb->data;
- unsigned int len = *p++;
+ unsigned int len;
*vc_fac_mask = 0;
@@ -50,6 +50,14 @@
memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));
+ if (skb->len < 1)
+ return 0;
+
+ len = *p++;
+
+ if (len >= skb->len)
+ return -1;
+
while (len > 0) {
switch (*p & X25_FAC_CLASS_MASK) {
case X25_FAC_CLASS_A:
@@ -247,6 +255,8 @@
memcpy(new, ours, sizeof(*new));
len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
+ if (len < 0)
+ return len;
/*
* They want reverse charging, we won't accept it.