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authorEric Dumazet <edumazet@google.com>2017-08-16 11:09:12 -0700
committerDavid S. Miller <davem@davemloft.net>2017-08-16 16:28:47 -0700
commitc780a049f9bf442314335372c9abc4548bfe3e44 (patch)
tree9bfe8c76f75ea6d1dbc52efa95ff294d80d58c8a /include/net/ip.h
parent81fbfe8adaf38d4f5a98c19bebfd41c5d6acaee8 (diff)
downloadop-kernel-dev-c780a049f9bf442314335372c9abc4548bfe3e44.zip
op-kernel-dev-c780a049f9bf442314335372c9abc4548bfe3e44.tar.gz
ipv4: better IP_MAX_MTU enforcement
While working on yet another syzkaller report, I found that our IP_MAX_MTU enforcements were not properly done. gcc seems to reload dev->mtu for min(dev->mtu, IP_MAX_MTU), and final result can be bigger than IP_MAX_MTU :/ This is a problem because device mtu can be changed on other cpus or threads. While this patch does not fix the issue I am working on, it is probably worth addressing it. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/ip.h')
-rw-r--r--include/net/ip.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/net/ip.h b/include/net/ip.h
index 821cedc..0cf7f5a 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -352,7 +352,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
!forwarding)
return dst_mtu(dst);
- return min(dst->dev->mtu, IP_MAX_MTU);
+ return min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU);
}
static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
@@ -364,7 +364,7 @@ static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
return ip_dst_mtu_maybe_forward(skb_dst(skb), forwarding);
}
- return min(skb_dst(skb)->dev->mtu, IP_MAX_MTU);
+ return min(READ_ONCE(skb_dst(skb)->dev->mtu), IP_MAX_MTU);
}
u32 ip_idents_reserve(u32 hash, int segs);
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