This is a note to let you know that I've just added the patch titled net: udp: annotate data race around udp_sk(sk)->corkflag to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-udp-annotate-data-race-around-udp_sk-sk-corkflag.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a9f5970767d11eadc805d5283f202612c7ba1f59 Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Mon, 27 Sep 2021 17:29:24 -0700 Subject: net: udp: annotate data race around udp_sk(sk)->corkflag From: Eric Dumazet <edumazet@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -1053,7 +1053,7 @@ 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; @@ -1361,7 +1361,7 @@ 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; @@ -2662,9 +2662,9 @@ 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); @@ -2787,7 +2787,7 @@ 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 @@ -1303,7 +1303,7 @@ 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 *); Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are queue-5.14/net-udp-annotate-data-race-around-udp_sk-sk-corkflag.patch queue-5.14/netfilter-log-work-around-missing-softdep-backend-mo.patch queue-5.14/af_unix-fix-races-in-sk_peer_pid-and-sk_peer_cred-ac.patch