From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 6 Jul 2022 23:40:00 +0000 (-0700)
Subject: net: Fix data-races around sysctl_mem.
X-Git-Tag: v4.19.253~34
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2934b8b53d899924f30c51372dfd39b1da9be6b1;p=thirdparty%2Fkernel%2Fstable.git

net: Fix data-races around sysctl_mem.

[ Upstream commit 310731e2f1611d1d13aae237abcf8e66d33345d5 ]

While reading .sysctl_mem, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/include/net/sock.h b/include/net/sock.h
index 7d3a4c2eea95b..98946f90781da 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1381,7 +1381,7 @@ void __sk_mem_reclaim(struct sock *sk, int amount);
 /* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */
 static inline long sk_prot_mem_limits(const struct sock *sk, int index)
 {
-	long val = sk->sk_prot->sysctl_mem[index];
+	long val = READ_ONCE(sk->sk_prot->sysctl_mem[index]);
 
 #if PAGE_SIZE > SK_MEM_QUANTUM
 	val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;