On Sun, May 12, 2019 at 04:49:39PM +0800, Gen Zhang wrote:
> On Sun, May 12, 2019 at 08:20:09AM +0200, Greg KH wrote:
> > Yes, that worked! Now, can you resend it in a proper format that I can
> > apply it in? (with changelog text, signed-off-by, etc.) as described in
> > Documentation/SubmittingPatches, I will be glad to review it after the
> > 5.2-rc1 release happens.
> >
> > thanks,
> >
> > greg k-h
> From: Gen Zhang <blackgod016...@gmail.com>
> Date: Sun, 11 May 2019 15:31:30 +0000
> Subject: [PATCH] vt: Fix a missing-check bug in drivers/tty/vt/vt.c file of
> Linux 5.0.14
Better, but no need for this to be in the body, just send it like any
other patch on the mailing list.
>
> Hi,
> I found this missing-check bug in drivers/tty/vt/vt.c when I was examining
> the source code.
That doesn't need to be in the changelog text.
>
> In function con_init(), the pointer variable vc_cons[currcons].d, vc and
> vc->vc_screenbuf is allocated a memory space via kzalloc().
> And they are used in the following codes.
Properly wrap your lines at 72 columns please.
>
> However, when there is a memory allocation error, kzalloc can be failed.
> Thus null pointer (vc_cons[currcons].d, vc and vc->vc_screenbuf) dereference
> may happen.
> And it will cause the kernel to crash. Therefore, we should check return
> value and handle an error.
>
> And this patch works in 5.1.1.
No need to say that.
>
> Thank you!
>
> Kind regards
> Gen
Or that :)
>
> Signed-off-by: Gen Zhang <blackgod016...@gmail.com>
> ---
> --- drivers/tty/vt/vt.c
> +++ drivers/tty/vt/vt.c
> @@ -3349,10 +3349,14 @@ static int __init con_init(void)
>
> for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) {
> vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data),
> GFP_NOWAIT);
> + if (!vc_cons[currcons].d || !vc)
> + goto err_vc;
What about the other memory that was allocated? You never free that.
> INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
> tty_port_init(&vc->port);
> visual_init(vc, currcons, 1);
> vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
> + if (!vc->vc_screenbuf)
> + goto err_vc_screenbuf;
Same here, you are now leaking memory.
Did you test this patch out with a kmalloc function that can fail? If
not, please try to do so.
thanks,
greg k-h
