net: Fix data-races around sysctl_mem.

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>

diff --git a/include/net/sock.h b/include/net/sock.h
index 72ca97ccb46072491179c1225f4e8bab85a7994f..9fa54762e07752313a181fec44df21794cdfc982 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1529,7 +1529,7 @@ 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;