Commit 4c17a496 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring/net: fix cleanup double free free_iov init 



Having ->async_data doesn't mean it's initialised and previously we vere
relying on setting F_CLEANUP at the right moment. With zc sendmsg
though, we set F_CLEANUP early in prep when we alloc a notif and so we
may allocate async_data, fail in copy_msg_hdr() leaving
struct io_async_msghdr not initialised correctly but with F_CLEANUP
set, which causes a ->free_iov double free and probably other nastiness.

Always initialise ->free_iov. Also, now it might point to fast_iov when
fails, so avoid freeing it during cleanups.

Reported-by: default avatar <syzbot+edfd15cd4246a3fc615a@syzkaller.appspotmail.com>
Fixes: 493108d9 ("io_uring/net: zerocopy sendmsg")
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent aa1df3a3

io_uring/net.c

+10 −10
Original line number Diff line number Diff line
@@ -124,20 +124,22 @@ static struct io_async_msghdr *io_msg_alloc_async(struct io_kiocb *req, 
{

	struct io_ring_ctx *ctx = req->ctx;

	struct io_cache_entry *entry;

	struct io_async_msghdr *hdr;



	if (!(issue_flags & IO_URING_F_UNLOCKED) &&

	    (entry = io_alloc_cache_get(&ctx->netmsg_cache)) != NULL) {

		struct io_async_msghdr *hdr;



		hdr = container_of(entry, struct io_async_msghdr, cache);

		hdr->free_iov = NULL;

		req->flags |= REQ_F_ASYNC_DATA;

		req->async_data = hdr;

		return hdr;

	}



	if (!io_alloc_async_data(req))

		return req->async_data;



	if (!io_alloc_async_data(req)) {

		hdr = req->async_data;

		hdr->free_iov = NULL;

		return hdr;

	}

	return NULL;

}
@@ -192,7 +194,6 @@ int io_send_prep_async(struct io_kiocb *req) 
	io = io_msg_alloc_async_prep(req);

	if (!io)

		return -ENOMEM;

	io->free_iov = NULL;

	ret = move_addr_to_kernel(zc->addr, zc->addr_len, &io->addr);

	return ret;

}
@@ -209,7 +210,6 @@ static int io_setup_async_addr(struct io_kiocb *req, 
	io = io_msg_alloc_async(req, issue_flags);

	if (!io)

		return -ENOMEM;

	io->free_iov = NULL;

	memcpy(&io->addr, addr_storage, sizeof(io->addr));

	return -EAGAIN;

}
@@ -479,7 +479,6 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req, 


		if (msg.msg_iovlen == 0) {

			sr->len = 0;

			iomsg->free_iov = NULL;

		} else if (msg.msg_iovlen > 1) {

			return -EINVAL;

		} else {
@@ -490,7 +489,6 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req, 
			if (clen < 0)

				return -EINVAL;

			sr->len = clen;

			iomsg->free_iov = NULL;

		}



		if (req->flags & REQ_F_APOLL_MULTISHOT) {
@@ -913,6 +911,8 @@ void io_send_zc_cleanup(struct io_kiocb *req) 


	if (req_has_async_data(req)) {

		io = req->async_data;

		/* might be ->fast_iov if *msg_copy_hdr failed */

		if (io->free_iov != io->fast_iov)

			kfree(io->free_iov);

	}

	if (zc->notif) {