Commit 11a4d6f6 authored by Tung Nguyen's avatar Tung Nguyen Committed by Jakub Kicinski
Browse files

tipc: fix kernel warning when sending SYN message 



When sending a SYN message, this kernel stack trace is observed:

...
[   13.396352] RIP: 0010:_copy_from_iter+0xb4/0x550
...
[   13.398494] Call Trace:
[   13.398630]  <TASK>
[   13.398630]  ? __alloc_skb+0xed/0x1a0
[   13.398630]  tipc_msg_build+0x12c/0x670 [tipc]
[   13.398630]  ? shmem_add_to_page_cache.isra.71+0x151/0x290
[   13.398630]  __tipc_sendmsg+0x2d1/0x710 [tipc]
[   13.398630]  ? tipc_connect+0x1d9/0x230 [tipc]
[   13.398630]  ? __local_bh_enable_ip+0x37/0x80
[   13.398630]  tipc_connect+0x1d9/0x230 [tipc]
[   13.398630]  ? __sys_connect+0x9f/0xd0
[   13.398630]  __sys_connect+0x9f/0xd0
[   13.398630]  ? preempt_count_add+0x4d/0xa0
[   13.398630]  ? fpregs_assert_state_consistent+0x22/0x50
[   13.398630]  __x64_sys_connect+0x16/0x20
[   13.398630]  do_syscall_64+0x42/0x90
[   13.398630]  entry_SYSCALL_64_after_hwframe+0x63/0xcd

It is because commit a41dad90 ("iov_iter: saner checks for attempt
to copy to/from iterator") has introduced sanity check for copying
from/to iov iterator. Lacking of copy direction from the iterator
viewpoint would lead to kernel stack trace like above.

This commit fixes this issue by initializing the iov iterator with
the correct copy direction when sending SYN or ACK without data.

Fixes: f25dcc76 ("tipc: tipc ->sendmsg() conversion")
Reported-by: default avatar <syzbot+d43608d061e8847ec9f3@syzkaller.appspotmail.com>
Acked-by: default avatarJon Maloy <jmaloy@redhat.com>
Signed-off-by: default avatarTung Nguyen <tung.q.nguyen@dektech.com.au>
Link: https://lore.kernel.org/r/20230214012606.5804-1-tung.q.nguyen@dektech.com.au


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 207ce626

net/tipc/socket.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -2614,6 +2614,7 @@ static int tipc_connect(struct socket *sock, struct sockaddr *dest, 
		/* Send a 'SYN-' to destination */

		/* Send a 'SYN-' to destination */

		m.msg_name = dest;

		m.msg_name = dest;

		m.msg_namelen = destlen;

		m.msg_namelen = destlen;

		iov_iter_kvec(&m.msg_iter, ITER_SOURCE, NULL, 0, 0);





		/* If connect is in non-blocking case, set MSG_DONTWAIT to

		/* If connect is in non-blocking case, set MSG_DONTWAIT to

		 * indicate send_msg() is never blocked.

		 * indicate send_msg() is never blocked.
@@ -2776,6 +2777,7 @@ static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags, 
		__skb_queue_head(&new_sk->sk_receive_queue, buf);

		__skb_queue_head(&new_sk->sk_receive_queue, buf);

		skb_set_owner_r(buf, new_sk);

		skb_set_owner_r(buf, new_sk);

	}

	}

	iov_iter_kvec(&m.msg_iter, ITER_SOURCE, NULL, 0, 0);

	__tipc_sendstream(new_sock, &m, 0);

	__tipc_sendstream(new_sock, &m, 0);

	release_sock(new_sk);

	release_sock(new_sk);

exit:

exit: