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authorEric Dumazet <edumazet@google.com>2017-12-11 07:17:39 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-02 20:35:10 +0100
commitc2f78bf8ca3aa18e51f1de41093db5adae2c5f34 (patch)
tree031e6d39f3ceb1b4962b2b58af9f1c7851bc8743 /include/net
parentb929ccccbc8c22736d1fd722da181e275465f5a6 (diff)
ipv4: igmp: guard against silly MTU values
[ Upstream commit b5476022bbada3764609368f03329ca287528dc8 ] IPv4 stack reacts to changes to small MTU, by disabling itself under RTNL. But there is a window where threads not using RTNL can see a wrong device mtu. This can lead to surprises, in igmp code where it is assumed the mtu is suitable. Fix this by reading device mtu once and checking IPv4 minimal MTU. This patch adds missing IPV4_MIN_MTU define, to not abuse ETH_MIN_MTU anymore. 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 'include/net')
-rw-r--r--include/net/ip.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/ip.h b/include/net/ip.h
index 51c6b9786c46..0e3dcd5a134d 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -33,6 +33,8 @@
#include <net/flow.h>
#include <net/flow_dissector.h>
+#define IPV4_MIN_MTU 68 /* RFC 791 */
+
struct sock;
struct inet_skb_parm {