[PATCH] cx231xx: correctly handling failed allocation

[PATCH] cx231xx: correctly handling failed allocation

[Insu Yun]

Since kmalloc can be failed in memory pressure, 
if not properly handled, NULL dereference can be happend

Signed-off-by: Insu Yun <wuninsu@gmail.com>
---
 drivers/media/usb/cx231xx/cx231xx-417.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/media/usb/cx231xx/cx231xx-417.c b/drivers/media/usb/cx231xx/cx231xx-417.c
index 47a98a2..9725e4f 100644
--- a/drivers/media/usb/cx231xx/cx231xx-417.c
+++ b/drivers/media/usb/cx231xx/cx231xx-417.c
@@ -1382,6 +1382,8 @@ static int cx231xx_bulk_copy(struct cx231xx *dev, struct urb *urb)
 	buffer_size = urb->actual_length;
 
 	buffer = kmalloc(buffer_size, GFP_ATOMIC);
+	if (!buffer)
+		return -ENOMEM;
 
 	memcpy(buffer, dma_q->ps_head, 3);
 	memcpy(buffer+3, p_buffer, buffer_size-3);
-- 
1.9.1

Re: [PATCH] cx231xx: correctly handling failed allocation

[Devin Heitmueller]

On Tue, Dec 29, 2015 at 1:53 PM, Insu Yun <wuninsu@gmail.com> wrote:
> Since kmalloc can be failed in memory pressure,
> if not properly handled, NULL dereference can be happend
>
> Signed-off-by: Insu Yun <wuninsu@gmail.com>
> ---
>  drivers/media/usb/cx231xx/cx231xx-417.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/media/usb/cx231xx/cx231xx-417.c b/drivers/media/usb/cx231xx/cx231xx-417.c
> index 47a98a2..9725e4f 100644
> --- a/drivers/media/usb/cx231xx/cx231xx-417.c
> +++ b/drivers/media/usb/cx231xx/cx231xx-417.c
> @@ -1382,6 +1382,8 @@ static int cx231xx_bulk_copy(struct cx231xx *dev, struct urb *urb)
>         buffer_size = urb->actual_length;
>
>         buffer = kmalloc(buffer_size, GFP_ATOMIC);
> +       if (!buffer)
> +               return -ENOMEM;

A kmalloc() call inside a bulk handler running in softirq context?
That doesn't look right.

That said, I don't have any specific objection to the patch (which I'm
assuming came from some automated tool), but I suspect the cx231xx-417
code is probably completely broken.  The only device I've ever seen
that has the cx23102 and cx23417 is one of the Polaris EVKs, which
AFAIK nobody has ever shipped a production design based on.

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com