net: Fix data-races around sysctl_mem.

q2ven · davem330 · commit 310731e2f161 · 2022-07-08T12:10:33.000+01:00
While reading .sysctl_mem, it can be changed concurrently. So, we need to add READ_ONCE() to avoid data-races. Fixes: 1da177e ("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
@@ -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;

Original file line number	Diff line number	Diff line change
`@@ -1529,7 +1529,7 @@ void __sk_mem_reclaim(struct sock *sk, int amount);`
`1529`	`1529`	`/* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */`
`1530`	`1530`	`static inline long sk_prot_mem_limits(const struct sock *sk, int index)`
`1531`	`1531`	`{`
`1532`		`- long val = sk->sk_prot->sysctl_mem[index];`
	`1532`	`+ long val = READ_ONCE(sk->sk_prot->sysctl_mem[index]);`
`1533`	`1533`
`1534`	`1534`	`#if PAGE_SIZE > SK_MEM_QUANTUM`
`1535`	`1535`	`val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;`