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 7d49196a3880ef6057b62fc53f9e74735f9a5b1e..96f51d4b164997f943f206a5d0f04d673104e7e4 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1484,7 +1484,7 @@ 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;