Re: [PATCH v2] io_uring/net: ensure compat import handlers clear free_iov

[Jiri Slaby <jirislaby@kernel.org>]

On 19. 12. 22, 15:36, Jens Axboe wrote:
> 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>

Tested-by: Jiri Slaby <jirislaby@kernel.org>


> ---
> 
> v2: let's play it a bit safer and just always clear at the top rather
>      in the individual cases.
> 
> diff --git a/io_uring/net.c b/io_uring/net.c
> index 5229976cb582..f76b688f476e 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -494,6 +494,7 @@ 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) {
> 

thanks,
-- 
js
suse labs