[PATCH] io_uring/net: ensure compat import handlers clear free_iov

[Jens Axboe <axboe@kernel.dk>]

If we're not allocating the vectors because the count is below
UIO_FASTIOV, we still do need to properly clear ->free_iov to prevent
an erronous free of on-stack data.

Reported-by: Jiri Slaby <jirislaby@gmail.com>
Fixes: 4c17a496a7a0 ("io_uring/net: fix cleanup double free free_iov init")
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/io_uring/net.c b/io_uring/net.c
index 5229976cb582..5aebdfd05de7 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -496,6 +496,7 @@ 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 {
@@ -506,6 +507,7 @@ 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) {
-- 
Jens Axboe