From: Eric Dumazet <edumazet@google.com>
Date: Wed, 28 Feb 2024 13:54:28 +0000 (+0000)
Subject: ipv6: annotate data-races around cnf.mtu6
X-Git-Tag: block-6.9-20240315~27^2~141^2~11
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=e7135f484994494a38071e3653a83d21d305f50c;p=linux-block.git

ipv6: annotate data-races around cnf.mtu6

idev->cnf.mtu6 might be read locklessly, add appropriate READ_ONCE()
and WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 52a51c69aa9d..a30c6aa9e5cf 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -332,7 +332,7 @@ static inline unsigned int ip6_dst_mtu_maybe_forward(const struct dst_entry *dst
 	rcu_read_lock();
 	idev = __in6_dev_get(dst->dev);
 	if (idev)
-		mtu = idev->cnf.mtu6;
+		mtu = READ_ONCE(idev->cnf.mtu6);
 	rcu_read_unlock();
 
 out:
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6975685f55ea..1b534edc7ca2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3671,7 +3671,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 
 		if (idev) {
 			rt6_mtu_change(dev, dev->mtu);
-			idev->cnf.mtu6 = dev->mtu;
+			WRITE_ONCE(idev->cnf.mtu6, dev->mtu);
 			break;
 		}
 
@@ -3763,7 +3763,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 			if (idev->cnf.mtu6 != dev->mtu &&
 			    dev->mtu >= IPV6_MIN_MTU) {
 				rt6_mtu_change(dev, dev->mtu);
-				idev->cnf.mtu6 = dev->mtu;
+				WRITE_ONCE(idev->cnf.mtu6, dev->mtu);
 			}
 			WRITE_ONCE(idev->tstamp, jiffies);
 			inet6_ifinfo_notify(RTM_NEWLINK, idev);
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 8523f0595b01..e96d79cd34d2 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1578,8 +1578,8 @@ skip_routeinfo:
 
 		if (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) {
 			ND_PRINTK(2, warn, "RA: invalid mtu: %d\n", mtu);
-		} else if (in6_dev->cnf.mtu6 != mtu) {
-			in6_dev->cnf.mtu6 = mtu;
+		} else if (READ_ONCE(in6_dev->cnf.mtu6) != mtu) {
+			WRITE_ONCE(in6_dev->cnf.mtu6, mtu);
 			fib6_metric_set(rt, RTAX_MTU, mtu);
 			rt6_mtu_change(skb->dev, mtu);
 		}
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 707d65bc9c0e..66c685b0b619 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1596,7 +1596,7 @@ static unsigned int fib6_mtu(const struct fib6_result *res)
 
 		rcu_read_lock();
 		idev = __in6_dev_get(dev);
-		mtu = idev->cnf.mtu6;
+		mtu = READ_ONCE(idev->cnf.mtu6);
 		rcu_read_unlock();
 	}
 
@@ -3249,8 +3249,8 @@ u32 ip6_mtu_from_fib6(const struct fib6_result *res,
 
 		mtu = IPV6_MIN_MTU;
 		idev = __in6_dev_get(dev);
-		if (idev && idev->cnf.mtu6 > mtu)
-			mtu = idev->cnf.mtu6;
+		if (idev)
+			mtu = max_t(u32, mtu, READ_ONCE(idev->cnf.mtu6));
 	}
 
 	mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);