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_dev.c b/net/x25/x25_dev.c
index e547ca1..fa2b418 100644
--- a/net/x25/x25_dev.c
+++ b/net/x25/x25_dev.c
@@ -32,6 +32,9 @@
unsigned short frametype;
unsigned int lci;
+ if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
+ return 0;
+
frametype = skb->data[2];
lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
@@ -115,6 +118,9 @@
goto drop;
}
+ if (!pskb_may_pull(skb, 1))
+ return 0;
+
switch (skb->data[0]) {
case X25_IFACE_DATA: