Re: [PATCH] io_uring: Initialize variable before use

[Muhammad Usama Anjum <musamaanjum@gmail.com>]

On Mon, 2021-03-22 at 23:41 +0500, Muhammad Usama Anjum wrote:
> 1) Initialize the struct msghdr msg in the start of the function
> 2) Uninitialized variable msg.msg_flags can get used if branch happens to
> out_free before initialization.
> 
> So initialize variable in question in the start of the function for
> simplicity in logic and use.
> 
> Addresses-Coverity: ("Uninitialized variable")
> Addresses-Coverity: ("Uninitialized variable read")
> Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
> ---
>  fs/io_uring.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index bba74631954b..d5f83326abff 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -4677,7 +4677,8 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>  {
>  	struct io_buffer *kbuf;
>  	struct io_sr_msg *sr = &req->sr_msg;
> -	struct msghdr msg;
> +	struct msghdr msg = {.msg_name = NULL, .msg_control = NULL, .msg_controllen = 0,
> +			     .msg_namelen = 0, .msg_iocb = NULL, .msg_flags = 0};
>  	void __user *buf = sr->buf;
>  	struct socket *sock;
>  	struct iovec iov;
> @@ -4701,13 +4702,6 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>  	if (unlikely(ret))
>  		goto out_free;
>  
> -	msg.msg_name = NULL;
> -	msg.msg_control = NULL;
> -	msg.msg_controllen = 0;
> -	msg.msg_namelen = 0;
> -	msg.msg_iocb = NULL;
> -	msg.msg_flags = 0;
> -
>  	flags = req->sr_msg.msg_flags | MSG_NOSIGNAL;
>  	if (flags & MSG_DONTWAIT)
>  		req->flags |= REQ_F_NOWAIT;

Reminder. Does anybody has any comments on it?