From a6bcfc89694ed8cb482a82cdc8b93aae63a8b691 Mon Sep 17 00:00:00 2001 From: Li RongQing Date: Fri, 3 Aug 2018 15:45:21 +0800 Subject: [PATCH] net: check extack._msg before print dev_set_mtu_ext is able to fail with a valid mtu value, at that condition, extack._msg is not set and random since it is in stack, then kernel will crash when print it. Fixes: 7a4c53bee3324a ("net: report invalid mtu value via netlink extack") Signed-off-by: Zhang Yu Signed-off-by: Li RongQing Signed-off-by: David S. Miller --- net/core/dev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index 36e994519488..f68122f0ab02 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -7583,8 +7583,9 @@ int dev_set_mtu(struct net_device *dev, int new_mtu) struct netlink_ext_ack extack; int err; + memset(&extack, 0, sizeof(extack)); err = dev_set_mtu_ext(dev, new_mtu, &extack); - if (err) + if (err && extack._msg) net_err_ratelimited("%s: %s\n", dev->name, extack._msg); return err; }