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xps: must clear sender_cpu before forwarding

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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: Eric Dumazet <edumazet@google.com>
Reported-by: John <jw@nuclearfallout.net>
Bisected-by: John <jw@nuclearfallout.net>
Fixes: 2bd82484bb ("xps: fix xps for stacked devices")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-03-11 18:42:02 -07:00 committed by David S. Miller
parent c8a4d29988
commit c29390c6df
4 changed files with 10 additions and 1 deletions
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7
include/linux/skbuff.h
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@ -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; 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 #ifdef NET_SKBUFF_DATA_USES_OFFSET
static inline unsigned char *skb_end_pointer(const struct sk_buff *skb) static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
{ {

2
net/core/skbuff.c
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@ -4173,7 +4173,7 @@ void skb_scrub_packet(struct sk_buff *skb, bool xnet)
skb->ignore_df = 0; skb->ignore_df = 0;
skb_dst_drop(skb); skb_dst_drop(skb);
skb->mark = 0; skb->mark = 0;
skb->sender_cpu = 0; skb_sender_cpu_clear(skb);
skb_init_secmark(skb); skb_init_secmark(skb);
secpath_reset(skb); secpath_reset(skb);
nf_reset(skb); nf_reset(skb);

1
net/ipv4/ip_forward.c
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@ -67,6 +67,7 @@ static int ip_forward_finish(struct sk_buff *skb)
if (unlikely(opt->optlen)) if (unlikely(opt->optlen))
ip_forward_options(skb); ip_forward_options(skb);
skb_sender_cpu_clear(skb);
return dst_output(skb); return dst_output(skb);
} }

1
net/ipv6/ip6_output.c
View File

@ -318,6 +318,7 @@ static int ip6_forward_proxy_check(struct sk_buff *skb)
static inline int ip6_forward_finish(struct sk_buff *skb) static inline int ip6_forward_finish(struct sk_buff *skb)
{ {
skb_sender_cpu_clear(skb);
return dst_output(skb); return dst_output(skb);
} }