From 6a1d1365fafe1b63e6c52ef72b40b1443a11f78c Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 14 Sep 2023 16:51:09 +0100 Subject: [PATCH] io_uring/net: fix iter retargeting for selected buf commit c21a8027ad8a68c340d0d58bf1cc61dcb0bc4d2f upstream. When using selected buffer feature, io_uring delays data iter setup until later. If io_setup_async_msg() is called before that it might see not correctly setup iterator. Pre-init nr_segs and judge from its state whether we repointing. Cc: stable@vger.kernel.org Reported-by: syzbot+a4c6e5ef999b68b26ed1@syzkaller.appspotmail.com Fixes: 0455d4ccec548 ("io_uring: add POLL_FIRST support for send/sendmsg and recv/recvmsg") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/0000000000002770be06053c7757@google.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/net.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/io_uring/net.c b/io_uring/net.c index 7245218fdbe2b..9fe1aada3ad00 100644 --- a/io_uring/net.c +++ b/io_uring/net.c @@ -170,6 +170,10 @@ static int io_setup_async_msg(struct io_kiocb *req, memcpy(async_msg, kmsg, sizeof(*kmsg)); if (async_msg->msg.msg_name) async_msg->msg.msg_name = &async_msg->addr; + + if ((req->flags & REQ_F_BUFFER_SELECT) && !async_msg->msg.msg_iter.nr_segs) + return -EAGAIN; + /* if were using fast_iov, set it to the new one */ if (!kmsg->free_iov) { size_t fast_idx = kmsg->msg.msg_iter.iov - kmsg->fast_iov; @@ -529,6 +533,7 @@ static int io_recvmsg_copy_hdr(struct io_kiocb *req, struct io_async_msghdr *iomsg) { iomsg->msg.msg_name = &iomsg->addr; + iomsg->msg.msg_iter.nr_segs = 0; #ifdef CONFIG_COMPAT if (req->ctx->compat)