From c29390c6dfeee0944ac6b5610ebbe403944378fc Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 11 Mar 2015 18:42:02 -0700
Subject: [PATCH] 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: Eric Dumazet <edumazet@google.com>
Reported-by: John <jw@nuclearfallout.net>
Bisected-by: John <jw@nuclearfallout.net>
Fixes: 2bd82484bb4c ("xps: fix xps for stacked devices")
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/skbuff.h | 7 +++++++
net/core/skbuff.c | 2 +-
net/ipv4/ip_forward.c | 1 +
net/ipv6/ip6_output.c | 1 +
4 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 30007afe70b3..f54d6659713a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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)
{
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f80507823531..434e78e5254d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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);
diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 787b3c294ce6..d9bc28ac5d1b 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -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);
}
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 0a04a37305d5..7e80b61b51ff 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -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);
}
--
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