* [PATCH] net: gro: fix possible panic in skb_gro_receive()
@ 2012-12-06 23:54 Eric Dumazet
2012-12-07 19:41 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2012-12-06 23:54 UTC (permalink / raw)
To: David Miller; +Cc: netdev
From: Eric Dumazet <edumazet@google.com>
commit 2e71a6f8084e (net: gro: selective flush of packets) added
a bug for skbs using frag_list. This part of the GRO stack is rarely
used, as it needs skb not using a page fragment for their skb->head.
Most drivers do use a page fragment, but some of them use GFP_KERNEL
allocations for the initial fill of their RX ring buffer.
napi_gro_flush() overwrite skb->prev that was used for these skb to
point to the last skb in frag_list.
Fix this using a separate field in struct napi_gro_cb to point to the
last fragment.
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
include/linux/netdevice.h | 3 +++
net/core/dev.c | 2 ++
net/core/skbuff.c | 6 +++---
3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f8eda02..a848ffc 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1488,6 +1488,9 @@ struct napi_gro_cb {
/* Used in ipv6_gro_receive() */
int proto;
+
+ /* used in skb_gro_receive() slow path */
+ struct sk_buff *last;
};
#define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb)
diff --git a/net/core/dev.c b/net/core/dev.c
index c0946cb..e5942bf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3451,6 +3451,8 @@ static int napi_gro_complete(struct sk_buff *skb)
struct list_head *head = &ptype_base[ntohs(type) & PTYPE_HASH_MASK];
int err = -ENOENT;
+ BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
+
if (NAPI_GRO_CB(skb)->count == 1) {
skb_shinfo(skb)->gso_size = 0;
goto out;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4007c14..3f0636c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3004,7 +3004,7 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
skb_shinfo(nskb)->gso_size = pinfo->gso_size;
pinfo->gso_size = 0;
skb_header_release(p);
- nskb->prev = p;
+ NAPI_GRO_CB(nskb)->last = p;
nskb->data_len += p->len;
nskb->truesize += p->truesize;
@@ -3030,8 +3030,8 @@ merge:
__skb_pull(skb, offset);
- p->prev->next = skb;
- p->prev = skb;
+ NAPI_GRO_CB(p)->last->next = skb;
+ NAPI_GRO_CB(p)->last = skb;
skb_header_release(skb);
done:
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] net: gro: fix possible panic in skb_gro_receive()
2012-12-06 23:54 [PATCH] net: gro: fix possible panic in skb_gro_receive() Eric Dumazet
@ 2012-12-07 19:41 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2012-12-07 19:41 UTC (permalink / raw)
To: eric.dumazet; +Cc: netdev
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 06 Dec 2012 15:54:59 -0800
> From: Eric Dumazet <edumazet@google.com>
>
> commit 2e71a6f8084e (net: gro: selective flush of packets) added
> a bug for skbs using frag_list. This part of the GRO stack is rarely
> used, as it needs skb not using a page fragment for their skb->head.
>
> Most drivers do use a page fragment, but some of them use GFP_KERNEL
> allocations for the initial fill of their RX ring buffer.
>
> napi_gro_flush() overwrite skb->prev that was used for these skb to
> point to the last skb in frag_list.
>
> Fix this using a separate field in struct napi_gro_cb to point to the
> last fragment.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied, thanks Eric.
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