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authorJohn Hughes <john@calva.com>2010-04-08 08:29:25 +0400
committerDavid S. Miller <davem@davemloft.net>2010-04-08 08:29:25 +0400
commitf5eb917b861828da18dc28854308068c66d1449a (patch)
treeaa45d1a809abbe426b55dc89b8167e5a6609d418 /net/x25/af_x25.c
parentfd218cf9557b9bf7061365a8fe7020a56d3f767c (diff)
downloadlinux-f5eb917b861828da18dc28854308068c66d1449a.tar.xz
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>
Diffstat (limited to 'net/x25/af_x25.c')
-rw-r--r--net/x25/af_x25.c47
1 files changed, 46 insertions, 1 deletions
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 9796f3ed1edb..fe26c01ef3e6 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -82,6 +82,41 @@ struct compat_x25_subscrip_struct {
};
#endif
+
+int x25_parse_address_block(struct sk_buff *skb,
+ struct x25_address *called_addr,
+ struct x25_address *calling_addr)
+{
+ unsigned char len;
+ int needed;
+ int rc;
+
+ if (skb->len < 1) {
+ /* packet has no address block */
+ rc = 0;
+ goto empty;
+ }
+
+ len = *skb->data;
+ needed = 1 + (len >> 4) + (len & 0x0f);
+
+ if (skb->len < needed) {
+ /* packet is too short to hold the addresses it claims
+ to hold */
+ rc = -1;
+ goto empty;
+ }
+
+ return x25_addr_ntoa(skb->data, called_addr, calling_addr);
+
+empty:
+ *called_addr->x25_addr = 0;
+ *calling_addr->x25_addr = 0;
+
+ return rc;
+}
+
+
int x25_addr_ntoa(unsigned char *p, struct x25_address *called_addr,
struct x25_address *calling_addr)
{
@@ -921,16 +956,26 @@ int x25_rx_call_request(struct sk_buff *skb, struct x25_neigh *nb,
/*
* Extract the X.25 addresses and convert them to ASCII strings,
* and remove them.
+ *
+ * Address block is mandatory in call request packets
*/
- addr_len = x25_addr_ntoa(skb->data, &source_addr, &dest_addr);
+ addr_len = x25_parse_address_block(skb, &source_addr, &dest_addr);
+ if (addr_len <= 0)
+ goto out_clear_request;
skb_pull(skb, addr_len);
/*
* Get the length of the facilities, skip past them for the moment
* get the call user data because this is needed to determine
* the correct listener
+ *
+ * Facilities length is mandatory in call request packets
*/
+ if (skb->len < 1)
+ goto out_clear_request;
len = skb->data[0] + 1;
+ if (skb->len < len)
+ goto out_clear_request;
skb_pull(skb,len);
/*