[PATCH 5.4 45/56] net: udp: annotate data race around udp_sk(sk)->corkflag

Greg Kroah-Hartman
2021-10-04T13:17:51Z

From: Eric Dumazet <edumazet@google.com>

commit a9f5970767d11eadc805d5283f202612c7ba1f59 upstream.

up->corkflag field can be read or written without any lock.
Annotate accesses to avoid possible syzbot/KCSAN reports.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/udp.c | 10 +++++-----
net/ipv6/udp.c | 2 +-
2 files changed, 6 insertions(+), 6 deletions(-)

--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -981,7 +981,7 @@ int udp_sendmsg(struct sock *sk, struct
__be16 dport;
u8 tos;
int err, is_udplite = IS_UDPLITE(sk);
- int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
+ int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
struct sk_buff *skb;
struct ip_options_data opt_copy;
@@ -1289,7 +1289,7 @@ int udp_sendpage(struct sock *sk, struct
}

up->len += size;
- if (!(up->corkflag || (flags&MSG_MORE)))
+ if (!(READ_ONCE(up->corkflag) || (flags&MSG_MORE)))
ret = udp_push_pending_frames(sk);
if (!ret)
ret = size;
@@ -2551,9 +2551,9 @@ int udp_lib_setsockopt(struct sock *sk,
switch (optname) {
case UDP_CORK:
if (val != 0) {
- up->corkflag = 1;
+ WRITE_ONCE(up->corkflag, 1);
} else {
- up->corkflag = 0;
+ WRITE_ONCE(up->corkflag, 0);
lock_sock(sk);
push_pending_frames(sk);
release_sock(sk);
@@ -2676,7 +2676,7 @@ int udp_lib_getsockopt(struct sock *sk,

switch (optname) {
case UDP_CORK:
- val = up->corkflag;
+ val = READ_ONCE(up->corkflag);
break;

case UDP_ENCAP:
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1231,7 +1231,7 @@ int udpv6_sendmsg(struct sock *sk, struc
int addr_len = msg->msg_namelen;
bool connected = false;
int ulen = len;
- int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
+ int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
int err;
int is_udplite = IS_UDPLITE(sk);
int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);