net: gro: fix possible panic in skb_gro_receive()
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 @@
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 @@
__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: