diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-08-16 11:09:12 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-30 10:21:40 +0200 |
| commit | f29c9f46af4ac2540713e43981ded8588e03ae3b (patch) | |
| tree | 93fa568b95c657a95c6bbfeca2a35ce2e4bcec05 /net | |
| parent | 59af5b87695de8e2c772827798938d8e35b49d05 (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.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6cd49fd17ac0..6a5b7783932e 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1247,7 +1247,7 @@ 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) |