Subject: [PATCH net-2.6] sundance: Fix oopses with corrupted skb_shared_info

From: Jarek Poplawski <[email-masked]>
Date: Sat, 25 Dec 2010 16:12:17 +0100

[Was: Help: major pppoe regression since 2.6.35 (panic on first ppp
conection)?]

On Sat, Dec 25, 2010 at 01:51:05PM +0000, Joel Soete wrote:
> Hello Jarek,
Hello Joel,
...
> I don't have any more warnings :<)
> 
> Awesome job.

Awesome help.

Thanks and Happy New Year to you as well!
Jarek P.
-------------->

[PATCH net-2.6] sundance: Fix oopses with corrupted skb_shared_info

Joel Soete reported oopses at the beginning of pppoe connections since
v2.6.35. After debugging the bug was found in sundance skb allocation
and dma mapping code, where skb_reserve() bytes aren't taken into
account. This is an old bug, only uncovered by some change in 2.6.35.

Initial debugging patch by: Eric Dumazet <[email-masked]>

Reported-by: Joel Soete <[email-masked]>
Tested-by: Joel Soete <[email-masked]>
Signed-off-by: Jarek Poplawski <[email-masked]>
Cc: Eric Dumazet <[email-masked]>
---

diff --git a/drivers/net/sundance.c b/drivers/net/sundance.c
index 3ed2a67..b409d7e 100644
--- a/drivers/net/sundance.c
+++ b/drivers/net/sundance.c
@@ -1016,7 +1016,7 @@ static void init_ring(struct net_device *dev)
 
 	/* Fill in the Rx buffers.  Handle allocation failure gracefully. */
 	for (i = 0; i < RX_RING_SIZE; i++) {
-		struct sk_buff *skb = dev_alloc_skb(np->rx_buf_sz);
+		struct sk_buff *skb = dev_alloc_skb(np->rx_buf_sz + 2);
 		np->rx_skbuff[i] = skb;
 		if (skb == NULL)
 			break;
@@ -1407,7 +1407,7 @@ static void refill_rx (struct net_device *dev)
 		struct sk_buff *skb;
 		entry = np->dirty_rx % RX_RING_SIZE;
 		if (np->rx_skbuff[entry] == NULL) {
-			skb = dev_alloc_skb(np->rx_buf_sz);
+			skb = dev_alloc_skb(np->rx_buf_sz + 2);
 			np->rx_skbuff[entry] = skb;
 			if (skb == NULL)
 				break;		/* Better luck next round. */