[2.6.20.21 review 07/35] SNAP: Fix SNAP protocol header accesses.

Willy Tarreau
2007-10-13T14:50:37Z

[-- Attachment #1: 0034-SNAP-Fix-SNAP-protocol-header-accesses.patch --]
[-- Type: text/plain, Size: 1280 bytes --]

The snap_rcv code reads 5 bytes so we should make sure that
we have 5 bytes in the head before proceeding.

Based on diagnosis and fix by Evgeniy Polyakov, reported by
Alan J. Wylie.

Patch also kills the skb->sk assignment before kfree_skb
since it's redundant.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
net/802/psnap.c | 17 ++++++++++++-----
1 files changed, 12 insertions(+), 5 deletions(-)

Index: 2.6/net/802/psnap.c
===================================================================
--- 2.6.orig/net/802/psnap.c
+++ 2.6/net/802/psnap.c
@@ -55,6 +55,9 @@ static int snap_rcv(struct sk_buff *skb,
.type = __constant_htons(ETH_P_SNAP),
};

+ if (unlikely(!pskb_may_pull(skb, 5)))
+ goto drop;
+
rcu_read_lock();
proto = find_snap_client(skb->h.raw);
if (proto) {
@@ -62,14 +65,18 @@ static int snap_rcv(struct sk_buff *skb,
skb->h.raw += 5;
skb_pull_rcsum(skb, 5);
rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
- } else {
- skb->sk = NULL;
- kfree_skb(skb);
- rc = 1;
}
-
rcu_read_unlock();
+
+ if (unlikely(!proto))
+ goto drop;
+
+out:
return rc;
+
+drop:
+ kfree_skb(skb);
+ goto out;
}

/*

--