From: Boris Sukholitko boris.sukholitko@broadcom.com
[ Upstream commit c0bbbdc32febd4f034ecbf3ea17865785b2c0652 ]
__netif_receive_skb_core may change the skb pointer passed into it (e.g. in rx_handler). The original skb may be freed as a result of this operation.
The callers of __netif_receive_skb_core may further process original skb by using pt_prev pointer returned by __netif_receive_skb_core thus leading to unpleasant effects.
The solution is to pass skb by reference into __netif_receive_skb_core.
v2: Added Fixes tag and comment regarding ppt_prev and skb invariant.
Fixes: 88eb1944e18c ("net: core: propagate SKB lists through packet_type lookup") Signed-off-by: Boris Sukholitko boris.sukholitko@broadcom.com Acked-by: Edward Cree ecree@solarflare.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/dev.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)
--- a/net/core/dev.c +++ b/net/core/dev.c @@ -4713,11 +4713,12 @@ static inline int nf_ingress(struct sk_b return 0; }
-static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc, +static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc, struct packet_type **ppt_prev) { struct packet_type *ptype, *pt_prev; rx_handler_func_t *rx_handler; + struct sk_buff *skb = *pskb; struct net_device *orig_dev; bool deliver_exact = false; int ret = NET_RX_DROP; @@ -4748,8 +4749,10 @@ another_round: ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog), skb); preempt_enable();
- if (ret2 != XDP_PASS) - return NET_RX_DROP; + if (ret2 != XDP_PASS) { + ret = NET_RX_DROP; + goto out; + } skb_reset_mac_len(skb); }
@@ -4899,6 +4902,13 @@ drop: }
out: + /* The invariant here is that if *ppt_prev is not NULL + * then skb should also be non-NULL. + * + * Apparently *ppt_prev assignment above holds this invariant due to + * skb dereferencing near it. + */ + *pskb = skb; return ret; }
@@ -4908,7 +4918,7 @@ static int __netif_receive_skb_one_core( struct packet_type *pt_prev = NULL; int ret;
- ret = __netif_receive_skb_core(skb, pfmemalloc, &pt_prev); + ret = __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev); if (pt_prev) ret = INDIRECT_CALL_INET(pt_prev->func, ipv6_rcv, ip_rcv, skb, skb->dev, pt_prev, orig_dev); @@ -4986,7 +4996,7 @@ static void __netif_receive_skb_list_cor struct packet_type *pt_prev = NULL;
skb_list_del_init(skb); - __netif_receive_skb_core(skb, pfmemalloc, &pt_prev); + __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev); if (!pt_prev) continue; if (pt_curr != pt_prev || od_curr != orig_dev) {