In commit 5fa12739a53d ("net: ipv4: listify ip_rcv_finish") calling
dst_input(skb) was split-out. The ip_sublist_rcv_finish() just calls
dst_input(skb) in a loop.
The problem is that ip_sublist_rcv_finish() forgot to remove the SKB
from the list before invoking dst_input(). Further more we need to
clear skb->next as other parts of the network stack use another kind
of SKB lists for xmit_more (see dev_hard_start_xmit).
A crash occurs if e.g. dst_input() invoke ip_forward(), which calls
dst_output()/ip_output() that eventually calls __dev_queue_xmit() +
sch_direct_xmit(), and a crash occurs in validate_xmit_skb_list().
This patch only fixes the crash, but there is a huge potential for
a performance boost if we can pass an SKB-list through to ip_forward.
Fixes: 5fa12739a53d ("net: ipv4: listify ip_rcv_finish")
Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
---
Only driver sfc actually uses this, but I don't have this NIC, so I
tested this on mlx5, with my own changes to make it use
netif_receive_skb_list(),
but I'm not ready to upstream the mlx5 driver change yet.
net/ipv4/ip_input.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 1a3b6f32b1c9..3196cf58f418 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -530,8 +530,14 @@ static void ip_sublist_rcv_finish(struct list_head *head)
{
struct sk_buff *skb, *next;
- list_for_each_entry_safe(skb, next, head, list)
+ list_for_each_entry_safe(skb, next, head, list) {
+ list_del(&skb->list);
+ /* Handle ip{6}_forward case, as sch_direct_xmit have
+ * another kind of SKB-list usage (see validate_xmit_skb_list)
+ */
+ skb->next = NULL;
dst_input(skb);
+ }
}
static void ip_list_rcv_finish(struct net *net, struct sock *sk,
