| Message ID | 1445269391-30333-1-git-send-email-jon.maloy@ericsson.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Jon Maloy <jon.maloy@ericsson.com> Date: Mon, 19 Oct 2015 11:43:11 -0400 > In commit d999297c3dbbe ("tipc: reduce locking scope during packet reception") > we altered the packet retransmission function. Since then, when > restransmitting packets, we create a clone of the original buffer > using __pskb_copy(skb, MIN_H_SIZE), where MIN_H_SIZE is the size of > the area we want to have copied, but also the smallest possible TIPC > packet size. The value of MIN_H_SIZE is 24. > > Unfortunately, __pskb_copy() also has the effect that the headroom > of the cloned buffer takes the size MIN_H_SIZE. This is too small > for carrying the packet over the UDP tunnel bearer, which requires > a minimum headroom of 28 bytes. A change to just use pskb_copy() > lets the clone inherit the original headroom of 80 bytes, but also > assumes that the copied data area is of at least that size, something > that is not always the case. So that is not a viable solution. > > We now fix this by adding a check for sufficient headroom in the > transmit function of udp_media.c, and expanding it when necessary. > > Fixes: commit d999297c3dbbe ("tipc: reduce locking scope during packet reception") > Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Applied. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c index c170d31..6e648d9 100644 --- a/net/tipc/udp_media.c +++ b/net/tipc/udp_media.c @@ -52,6 +52,8 @@ /* IANA assigned UDP port */ #define UDP_PORT_DEFAULT 6118 +#define UDP_MIN_HEADROOM 28 + static const struct nla_policy tipc_nl_udp_policy[TIPC_NLA_UDP_MAX + 1] = { [TIPC_NLA_UDP_UNSPEC] = {.type = NLA_UNSPEC}, [TIPC_NLA_UDP_LOCAL] = {.type = NLA_BINARY, @@ -156,6 +158,9 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb, struct sk_buff *clone; struct rtable *rt; + if (skb_headroom(skb) < UDP_MIN_HEADROOM) + pskb_expand_head(skb, UDP_MIN_HEADROOM, 0, GFP_ATOMIC); + clone = skb_clone(skb, GFP_ATOMIC); skb_set_inner_protocol(clone, htons(ETH_P_TIPC)); ub = rcu_dereference_rtnl(b->media_ptr);
In commit d999297c3dbbe ("tipc: reduce locking scope during packet reception") we altered the packet retransmission function. Since then, when restransmitting packets, we create a clone of the original buffer using __pskb_copy(skb, MIN_H_SIZE), where MIN_H_SIZE is the size of the area we want to have copied, but also the smallest possible TIPC packet size. The value of MIN_H_SIZE is 24. Unfortunately, __pskb_copy() also has the effect that the headroom of the cloned buffer takes the size MIN_H_SIZE. This is too small for carrying the packet over the UDP tunnel bearer, which requires a minimum headroom of 28 bytes. A change to just use pskb_copy() lets the clone inherit the original headroom of 80 bytes, but also assumes that the copied data area is of at least that size, something that is not always the case. So that is not a viable solution. We now fix this by adding a check for sufficient headroom in the transmit function of udp_media.c, and expanding it when necessary. Fixes: commit d999297c3dbbe ("tipc: reduce locking scope during packet reception") Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> --- net/tipc/udp_media.c | 5 +++++ 1 file changed, 5 insertions(+)