Subject: [PATCH] [Bug 24472] Kernel panic - not syncing: Fatal Exception

From: Andrej Ota <[email-masked]>
Date: Fri, 10 Dec 2010 15:49:08 +0100

Move kfree_skb which was causing memory corruption to new location, while still keeping appropriate return value for function __pppoe_xmit. Prevents memory corruption and consequent kernel panic when PPPoE peer terminates the link.

Signed-off-by: Andrej Ota [[email-masked]]
Reported-by: Pawel Staszewski [[email-masked]]
---
 drivers/net/pppoe.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
index d72fb05..1a21dce 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -924,8 +924,10 @@ static int __pppoe_xmit(struct sock *sk, struct sk_buff *skb)
 	/* Copy the data if there is no space for the header or if it's
 	 * read-only.
 	 */
-	if (skb_cow_head(skb, sizeof(*ph) + dev->hard_header_len))
+	if (skb_cow_head(skb, sizeof(*ph) + dev->hard_header_len)) {
+		kfree_skb(skb);
 		goto abort;
+	}

 	__skb_push(skb, sizeof(*ph));
 	skb_reset_network_header(skb);
@@ -947,7 +949,6 @@ static int __pppoe_xmit(struct sock *sk, struct sk_buff *skb)
 	return 1;

 abort:
-	kfree_skb(skb);
 	return 0;
 }

---

Andrej Ota.