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authorEric Dumazet <edumazet@google.com>2017-08-16 11:09:12 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-30 10:19:19 +0200
commit1bd54371388c0c1e24e3ffa8afde9e130c5799b9 (patch)
tree796335838a30430ad4d09954ba8c0acaa8a0371c /net
parent7e1fe0062c24b1cdfb58fb494d03741a6b0a4ac8 (diff)
ipv4: better IP_MAX_MTU enforcement
[ Upstream commit c780a049f9bf442314335372c9abc4548bfe3e44 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/route.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index c295d882c6e0..0294f7c99c85 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1241,7 +1241,7 @@ static unsigned int ipv4_mtu(const struct dst_entry *dst)
if (mtu)
return mtu;
- mtu = dst->dev->mtu;
+ mtu = READ_ONCE(dst->dev->mtu);
if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
if (rt->rt_uses_gateway && mtu > 576)