This is a note to let you know that I've just added the patch titled
net: Fix load-tearing on sk->sk_stamp in sock_recv_cmsgs().
to the 5.4-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-fix-load-tearing-on-sk-sk_stamp-in-sock_recv_cms.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 630974577e55d07c8e56fe112ff7358fd9d8d018
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Mon May 8 10:55:43 2023 -0700
net: Fix load-tearing on sk->sk_stamp in sock_recv_cmsgs().
[ Upstream commit dfd9248c071a3710c24365897459538551cb7167 ]
KCSAN found a data race in sock_recv_cmsgs() where the read access
to sk->sk_stamp needs READ_ONCE().
BUG: KCSAN: data-race in packet_recvmsg / packet_recvmsg
write (marked) to 0xffff88803c81f258 of 8 bytes by task 19171 on cpu 0:
sock_write_timestamp include/net/sock.h:2670 [inline]
sock_recv_cmsgs include/net/sock.h:2722 [inline]
packet_recvmsg+0xb97/0xd00 net/packet/af_packet.c:3489
sock_recvmsg_nosec net/socket.c:1019 [inline]
sock_recvmsg+0x11a/0x130 net/socket.c:1040
sock_read_iter+0x176/0x220 net/socket.c:1118
call_read_iter include/linux/fs.h:1845 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x5e0/0x630 fs/read_write.c:470
ksys_read+0x163/0x1a0 fs/read_write.c:613
__do_sys_read fs/read_write.c:623 [inline]
__se_sys_read fs/read_write.c:621 [inline]
__x64_sys_read+0x41/0x50 fs/read_write.c:621
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc
read to 0xffff88803c81f258 of 8 bytes by task 19183 on cpu 1:
sock_recv_cmsgs include/net/sock.h:2721 [inline]
packet_recvmsg+0xb64/0xd00 net/packet/af_packet.c:3489
sock_recvmsg_nosec net/socket.c:1019 [inline]
sock_recvmsg+0x11a/0x130 net/socket.c:1040
sock_read_iter+0x176/0x220 net/socket.c:1118
call_read_iter include/linux/fs.h:1845 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x5e0/0x630 fs/read_write.c:470
ksys_read+0x163/0x1a0 fs/read_write.c:613
__do_sys_read fs/read_write.c:623 [inline]
__se_sys_read fs/read_write.c:621 [inline]
__x64_sys_read+0x41/0x50 fs/read_write.c:621
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc
value changed: 0xffffffffc4653600 -> 0x0000000000000000
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19183 Comm: syz-executor.5 Not tainted 6.3.0-rc7-02330-gca6270c12e20 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Fixes: 6c7c98bad488 ("sock: avoid dirtying sk_stamp, if possible")
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230508175543.55756-1-kuniyu@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/net/sock.h b/include/net/sock.h
index 26dd07e47a7c7..fa19c6ba24441 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2448,7 +2448,7 @@ static inline void sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
__sock_recv_ts_and_drops(msg, sk, skb);
else if (unlikely(sock_flag(sk, SOCK_TIMESTAMP)))
sock_write_timestamp(sk, skb->tstamp);
- else if (unlikely(sk->sk_stamp == SK_DEFAULT_STAMP))
+ else if (unlikely(sock_read_timestamp(sk) == SK_DEFAULT_STAMP))
sock_write_timestamp(sk, 0);
}
