diff options
| author | Boris Sukholitko <boris.sukholitko@broadcom.com> | 2020-05-19 10:32:37 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-05-19 15:38:00 -0700 |
| commit | c0bbbdc32febd4f034ecbf3ea17865785b2c0652 (patch) | |
| tree | a72795d0d8594c6b85681104a4240b9e5fc9c1a0 | |
| parent | 88d7fcfa3b1fe670f0412b95be785aafca63352b (diff) | |
| download | linux-c0bbbdc32febd4f034ecbf3ea17865785b2c0652.tar.bz2 | |
__netif_receive_skb_core: pass skb by reference
__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>
| -rw-r--r-- | net/core/dev.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 6d327b7aa813..2d8aceee4284 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4988,11 +4988,12 @@ static inline int nf_ingress(struct sk_buff *skb, struct packet_type **pt_prev, 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; @@ -5023,8 +5024,10 @@ 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); } @@ -5174,6 +5177,13 @@ 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; } @@ -5183,7 +5193,7 @@ static int __netif_receive_skb_one_core(struct sk_buff *skb, bool pfmemalloc) 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); @@ -5261,7 +5271,7 @@ static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemallo 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) { |