x25: Handle undersized/fragmented skbs
There are multiple locations in the X.25 packet layer where a skb is
assumed to be of at least a certain size and that all its data is
currently available at skb->data. These assumptions are not checked,
hence buffer overreads may occur. Use pskb_may_pull to check these
minimal size assumptions and ensure that data is available at skb->data
when necessary, as well as use skb_copy_bits where needed.
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Cc: stable <stable@kernel.org>
Acked-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c
index 037958f..4acacf3 100644
--- a/net/x25/x25_link.c
+++ b/net/x25/x25_link.c
@@ -90,6 +90,9 @@
break;
case X25_DIAGNOSTIC:
+ if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
+ break;
+
printk(KERN_WARNING "x25: diagnostic #%d - %02X %02X %02X\n",
skb->data[3], skb->data[4],
skb->data[5], skb->data[6]);
