4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit afe8764f76346ba838d4f162883e23d2fcfaa90e ]
sk->sk_shutdown is changed under unix_state_lock(sk), but unix_dgram_sendmsg() calls two functions to read sk_shutdown locklessly.
sock_alloc_send_pskb `- sock_wait_for_wmem
Let's use READ_ONCE() there.
Note that the writer side was marked by commit e1d09c2c2f57 ("af_unix: Fix data races around sk->sk_shutdown.").
BUG: KCSAN: data-race in sock_alloc_send_pskb / unix_release_sock
write (marked) to 0xffff8880069af12c of 1 bytes by task 1 on cpu 1: unix_release_sock+0x75c/0x910 net/unix/af_unix.c:631 unix_release+0x59/0x80 net/unix/af_unix.c:1053 __sock_release+0x7d/0x170 net/socket.c:654 sock_close+0x19/0x30 net/socket.c:1386 __fput+0x2a3/0x680 fs/file_table.c:384 ____fput+0x15/0x20 fs/file_table.c:412 task_work_run+0x116/0x1a0 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x174/0x180 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:297 do_syscall_64+0x4b/0x90 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
read to 0xffff8880069af12c of 1 bytes by task 28650 on cpu 0: sock_alloc_send_pskb+0xd2/0x620 net/core/sock.c:2767 unix_dgram_sendmsg+0x2f8/0x14f0 net/unix/af_unix.c:1944 unix_seqpacket_sendmsg net/unix/af_unix.c:2308 [inline] unix_seqpacket_sendmsg+0xba/0x130 net/unix/af_unix.c:2292 sock_sendmsg_nosec net/socket.c:725 [inline] sock_sendmsg+0x148/0x160 net/socket.c:748 ____sys_sendmsg+0x4e4/0x610 net/socket.c:2494 ___sys_sendmsg+0xc6/0x140 net/socket.c:2548 __sys_sendmsg+0x94/0x140 net/socket.c:2577 __do_sys_sendmsg net/socket.c:2586 [inline] __se_sys_sendmsg net/socket.c:2584 [inline] __x64_sys_sendmsg+0x45/0x50 net/socket.c:2584 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+0x6e/0xd8
value changed: 0x00 -> 0x03
Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 28650 Comm: systemd-coredum Not tainted 6.4.0-11989-g6843306689af #6 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzkaller syzkaller@googlegroups.com Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/sock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/sock.c b/net/core/sock.c index 1f76e7a78a8d1..846d4cec79903 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2065,7 +2065,7 @@ static long sock_wait_for_wmem(struct sock *sk, long timeo) prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); if (refcount_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) break; - if (sk->sk_shutdown & SEND_SHUTDOWN) + if (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) break; if (sk->sk_err) break; @@ -2095,7 +2095,7 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, goto failure;
err = -EPIPE; - if (sk->sk_shutdown & SEND_SHUTDOWN) + if (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) goto failure;
if (sk_wmem_alloc_get(sk) < sk->sk_sndbuf)