From 75f4479a870bc237ee9b029130898cade92dd054 Mon Sep 17 00:00:00 2001 From: Tung Nguyen Date: Tue, 14 Feb 2023 01:26:06 +0000 Subject: [PATCH] tipc: fix kernel warning when sending SYN message commit cdf5e5682206f8a9de5840d1c7c76a4169a203c5 upstream. 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] [ 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 9fca845620af ("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: 3cab21a0ab32 ("tipc: tipc ->sendmsg() conversion") Reported-by: syzbot+d43608d061e8847ec9f3@syzkaller.appspotmail.com Acked-by: Jon Maloy Signed-off-by: Tung Nguyen Link: https://lore.kernel.org/r/20230214012606.5804-1-tung.q.nguyen@dektech.com.au Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/tipc/socket.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/tipc/socket.c b/net/tipc/socket.c index e902b01ea3cb1..ff5bb9e4731c4 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -2614,6 +2614,7 @@ static int tipc_connect(struct socket *sock, struct sockaddr *dest, /* Send a 'SYN-' to destination */ m.msg_name = dest; 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 * 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_set_owner_r(buf, new_sk); } + iov_iter_kvec(&m.msg_iter, ITER_SOURCE, NULL, 0, 0); __tipc_sendstream(new_sock, &m, 0); release_sock(new_sk); exit: -- 2.39.5