From f5eb917b861828da18dc28854308068c66d1449a Mon Sep 17 00:00:00 2001 From: John Hughes Date: Wed, 7 Apr 2010 21:29:25 -0700 Subject: 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 Signed-off-by: David S. Miller --- net/x25/x25_facilities.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'net/x25/x25_facilities.c') 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 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, 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 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, 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 @@ int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, 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. -- cgit v1.1