From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon, 18 Jul 2022 17:26:39 +0000 (-0700)
Subject: ipv4: Fix a data-race around sysctl_fib_multipath_use_neigh.
X-Git-Tag: baikal/mips/sdk6.1~5282^2~3^2~14
X-Git-Url: https://git.baikalelectronics.ru/?a=commitdiff_plain;h=579b451998bfa384905861b10ca4bdb53e682ab6;p=kernel.git

ipv4: Fix a data-race around sysctl_fib_multipath_use_neigh.

While reading sysctl_fib_multipath_use_neigh, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its reader.

Fixes: f596ce6f4c9e ("net: ipv4: Consider failed nexthops in multipath routes")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index d9fdcbae16ee3..db7b2503f0682 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -2216,7 +2216,7 @@ void fib_select_multipath(struct fib_result *res, int hash)
 	}
 
 	change_nexthops(fi) {
-		if (net->ipv4.sysctl_fib_multipath_use_neigh) {
+		if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
 			if (!fib_good_nh(nexthop_nh))
 				continue;
 			if (!first) {