diff mbox series

[v2,net-next,04/10] net: core: add READ_ONCE/WRITE_ONCE annotations for sk->sk_bound_dev_if

Message ID 20220513185550.844558-5-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Commit e5fccaa1eb7f6116deab0f708a787e2de915869f
Delegated to: Netdev Maintainers
Headers show
Series [v2,net-next,01/10] net: annotate races around sk->sk_bound_dev_if | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 6 this patch: 6
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 6 this patch: 6
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 38 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet May 13, 2022, 6:55 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

sock_bindtoindex_locked() needs to use WRITE_ONCE(sk->sk_bound_dev_if, val),
because other cpus/threads might locklessly read this field.

sock_getbindtodevice(), sock_getsockopt() need READ_ONCE()
because they run without socket lock held.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/sock.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/core/sock.c b/net/core/sock.c
index 6b287eb5427b32865d25fc22122fefeff3a4ccf5..2500f9989117441a67ce2c457af25bf8f780b110 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -635,7 +635,9 @@  static int sock_bindtoindex_locked(struct sock *sk, int ifindex)
 	if (ifindex < 0)
 		goto out;
 
-	sk->sk_bound_dev_if = ifindex;
+	/* Paired with all READ_ONCE() done locklessly. */
+	WRITE_ONCE(sk->sk_bound_dev_if, ifindex);
+
 	if (sk->sk_prot->rehash)
 		sk->sk_prot->rehash(sk);
 	sk_dst_reset(sk);
@@ -713,10 +715,11 @@  static int sock_getbindtodevice(struct sock *sk, char __user *optval,
 {
 	int ret = -ENOPROTOOPT;
 #ifdef CONFIG_NETDEVICES
+	int bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
 	struct net *net = sock_net(sk);
 	char devname[IFNAMSIZ];
 
-	if (sk->sk_bound_dev_if == 0) {
+	if (bound_dev_if == 0) {
 		len = 0;
 		goto zero;
 	}
@@ -725,7 +728,7 @@  static int sock_getbindtodevice(struct sock *sk, char __user *optval,
 	if (len < IFNAMSIZ)
 		goto out;
 
-	ret = netdev_get_name(net, devname, sk->sk_bound_dev_if);
+	ret = netdev_get_name(net, devname, bound_dev_if);
 	if (ret)
 		goto out;
 
@@ -1861,7 +1864,7 @@  int sock_getsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case SO_BINDTOIFINDEX:
-		v.val = sk->sk_bound_dev_if;
+		v.val = READ_ONCE(sk->sk_bound_dev_if);
 		break;
 
 	case SO_NETNS_COOKIE: