Patch "net: fib_rules: annotate data-races around rule->[io]ifindex" has been added to the 6.13-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: fib_rules: annotate data-races around rule->[io]ifindex

to the 6.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-fib_rules-annotate-data-races-around-rule-io-ifi.patch
and it can be found in the queue-6.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 99405fe2d3d2b9b9c1e7bafff4b3c01a10e44021
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Thu Feb 6 08:30:51 2025 +0000

    net: fib_rules: annotate data-races around rule->[io]ifindex
    
    [ Upstream commit cb827db50a88aebec516151681adb6db10b688ee ]
    
    rule->iifindex and rule->oifindex can be read without holding RTNL.
    
    Add READ_ONCE()/WRITE_ONCE() annotations where needed.
    
    Fixes: 32affa5578f0 ("fib: rules: no longer hold RTNL in fib_nl_dumprule()")
    Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
    Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
    Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxx>
    Link: https://patch.msgid.link/20250206083051.2494877-1-edumazet@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 34185d138c95a..ff1cebd71f7b4 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -37,8 +37,8 @@ static const struct fib_kuid_range fib_kuid_range_unset = {
 
 bool fib_rule_matchall(const struct fib_rule *rule)
 {
-	if (rule->iifindex || rule->oifindex || rule->mark || rule->tun_id ||
-	    rule->flags)
+	if (READ_ONCE(rule->iifindex) || READ_ONCE(rule->oifindex) ||
+	    rule->mark || rule->tun_id || rule->flags)
 		return false;
 	if (rule->suppress_ifgroup != -1 || rule->suppress_prefixlen != -1)
 		return false;
@@ -261,12 +261,14 @@ static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
 			  struct flowi *fl, int flags,
 			  struct fib_lookup_arg *arg)
 {
-	int ret = 0;
+	int iifindex, oifindex, ret = 0;
 
-	if (rule->iifindex && (rule->iifindex != fl->flowi_iif))
+	iifindex = READ_ONCE(rule->iifindex);
+	if (iifindex && (iifindex != fl->flowi_iif))
 		goto out;
 
-	if (rule->oifindex && (rule->oifindex != fl->flowi_oif))
+	oifindex = READ_ONCE(rule->oifindex);
+	if (oifindex && (oifindex != fl->flowi_oif))
 		goto out;
 
 	if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
@@ -1039,14 +1041,14 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 	if (rule->iifname[0]) {
 		if (nla_put_string(skb, FRA_IIFNAME, rule->iifname))
 			goto nla_put_failure;
-		if (rule->iifindex == -1)
+		if (READ_ONCE(rule->iifindex) == -1)
 			frh->flags |= FIB_RULE_IIF_DETACHED;
 	}
 
 	if (rule->oifname[0]) {
 		if (nla_put_string(skb, FRA_OIFNAME, rule->oifname))
 			goto nla_put_failure;
-		if (rule->oifindex == -1)
+		if (READ_ONCE(rule->oifindex) == -1)
 			frh->flags |= FIB_RULE_OIF_DETACHED;
 	}
 
@@ -1218,10 +1220,10 @@ static void attach_rules(struct list_head *rules, struct net_device *dev)
 	list_for_each_entry(rule, rules, list) {
 		if (rule->iifindex == -1 &&
 		    strcmp(dev->name, rule->iifname) == 0)
-			rule->iifindex = dev->ifindex;
+			WRITE_ONCE(rule->iifindex, dev->ifindex);
 		if (rule->oifindex == -1 &&
 		    strcmp(dev->name, rule->oifname) == 0)
-			rule->oifindex = dev->ifindex;
+			WRITE_ONCE(rule->oifindex, dev->ifindex);
 	}
 }
 
@@ -1231,9 +1233,9 @@ static void detach_rules(struct list_head *rules, struct net_device *dev)
 
 	list_for_each_entry(rule, rules, list) {
 		if (rule->iifindex == dev->ifindex)
-			rule->iifindex = -1;
+			WRITE_ONCE(rule->iifindex, -1);
 		if (rule->oifindex == dev->ifindex)
-			rule->oifindex = -1;
+			WRITE_ONCE(rule->oifindex, -1);
 	}
 }