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| author | Cong Wang <cong.wang@bytedance.com> | 2021-05-08 20:00:33 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-05-10 23:33:10 +0200 |
| commit | a100243d95a60d74ae9bb9df1f5f2192e9aed6a7 (patch) | |
| tree | 5c614edec5ccc729eae58fb83e8ef43026f9e9ad /net/ipv4/devinet.c | |
| parent | Merge branch 'qca_spi-sync' (diff) | |
| download | linux-a100243d95a60d74ae9bb9df1f5f2192e9aed6a7.tar.xz linux-a100243d95a60d74ae9bb9df1f5f2192e9aed6a7.zip | |
rtnetlink: avoid RCU read lock when holding RTNL
When we call af_ops->set_link_af() we hold a RCU read lock
as we retrieve af_ops from the RCU protected list, but this
is unnecessary because we already hold RTNL lock, which is
the writer lock for protecting rtnl_af_ops, so it is safer
than RCU read lock. Similar for af_ops->validate_link_af().
This was not a problem until we begin to take mutex lock
down the path of ->set_link_af() in __ipv6_dev_mc_dec()
recently. We can just drop the RCU read lock there and
assert RTNL lock.
Reported-and-tested-by: syzbot+7d941e89dd48bcf42573@syzkaller.appspotmail.com
Fixes: 63ed8de4be81 ("mld: add mc_lock for protecting per-interface mld data")
Tested-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/devinet.c')
| -rw-r--r-- | net/ipv4/devinet.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 2e35f68da40a..50deeff48c8b 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1955,7 +1955,7 @@ static int inet_validate_link_af(const struct net_device *dev, struct nlattr *a, *tb[IFLA_INET_MAX+1]; int err, rem; - if (dev && !__in_dev_get_rcu(dev)) + if (dev && !__in_dev_get_rtnl(dev)) return -EAFNOSUPPORT; err = nla_parse_nested_deprecated(tb, IFLA_INET_MAX, nla, @@ -1981,7 +1981,7 @@ static int inet_validate_link_af(const struct net_device *dev, static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla, struct netlink_ext_ack *extack) { - struct in_device *in_dev = __in_dev_get_rcu(dev); + struct in_device *in_dev = __in_dev_get_rtnl(dev); struct nlattr *a, *tb[IFLA_INET_MAX+1]; int rem; |