io_uring/net: ensure compat import handlers clear free_iov

commit 990a4de57e44f4f4cfc33c90d2ec5d285b7c8342 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/net.c b/io_uring/net.c
index 03825b0..d19763d 100644 (file)
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -479,6 +479,7 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
        if (req->flags & REQ_F_BUFFER_SELECT) {
                compat_ssize_t clen;
 
+               iomsg->free_iov = NULL;
                if (msg.msg_iovlen == 0) {
                        sr->len = 0;
                } else if (msg.msg_iovlen > 1) {