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Commit c29390c6 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

xps: must clear sender_cpu before forwarding 



John reported that my previous commit added a regression
on his router.

This is because sender_cpu & napi_id share a common location,
so get_xps_queue() can see garbage and perform an out of bound access.

We need to make sure sender_cpu is cleared before doing the transmit,
otherwise any NIC busy poll enabled (skb_mark_napi_id()) can trigger
this bug.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarJohn <jw@nuclearfallout.net>
Bisected-by: default avatarJohn <jw@nuclearfallout.net>
Fixes: 2bd82484 ("xps: fix xps for stacked devices")
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c8a4d299

include/linux/skbuff.h

+7 −0
Original line number Diff line number Diff line
@@ -948,6 +948,13 @@ static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from) 
	to->l4_hash = from->l4_hash;

};



static inline void skb_sender_cpu_clear(struct sk_buff *skb)

{

#ifdef CONFIG_XPS

	skb->sender_cpu = 0;

#endif

}



#ifdef NET_SKBUFF_DATA_USES_OFFSET

static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)

{

net/core/skbuff.c

+1 −1
Original line number Diff line number Diff line
@@ -4173,7 +4173,7 @@ void skb_scrub_packet(struct sk_buff *skb, bool xnet) 
	skb->ignore_df = 0;

	skb_dst_drop(skb);

	skb->mark = 0;

	skb->sender_cpu = 0;

	skb_sender_cpu_clear(skb);

	skb_init_secmark(skb);

	secpath_reset(skb);

	nf_reset(skb);

net/ipv4/ip_forward.c

+1 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ static int ip_forward_finish(struct sk_buff *skb) 
	if (unlikely(opt->optlen))

		ip_forward_options(skb);



	skb_sender_cpu_clear(skb);

	return dst_output(skb);

}

net/ipv6/ip6_output.c

+1 −0
Original line number Diff line number Diff line
@@ -318,6 +318,7 @@ static int ip6_forward_proxy_check(struct sk_buff *skb) 


static inline int ip6_forward_finish(struct sk_buff *skb)

{

	skb_sender_cpu_clear(skb);

	return dst_output(skb);

}