linux-kernel - Re: [PATCH V2] drivers/media/v4l2-core/videobuf2-core.c: fix error return code

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Message-ID: <CALF0-+WPZ7b83Mg=b1KirHt39QE4fuO4MDGhNpQNxMY09O87HA@mail.gmail.com>
Date:	Thu, 18 Oct 2012 12:28:15 -0300
From:	Ezequiel Garcia <elezegarcia@...il.com>
To:	Peter Senna Tschudin <peter.senna@...il.com>
Cc:	pawel@...iak.com, m.szyprowski@...sung.com,
	kyungmin.park@...sung.com, mchehab@...radead.org,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH V2] drivers/media/v4l2-core/videobuf2-core.c: fix error
 return code

On Thu, Oct 18, 2012 at 11:47 AM, Peter Senna Tschudin
<peter.senna@...il.com> wrote:
> This patch fixes a NULL pointer dereference bug at __vb2_init_fileio().
> The NULL pointer deference happens at videobuf2-core.c:
>
> static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_t count,
>                 loff_t *ppos, int nonblock, int read)
> {
> ...
>         if (!q->fileio) {
>                 ret = __vb2_init_fileio(q, read);
>                 dprintk(3, "file io: vb2_init_fileio result: %d\n", ret);
>                 if (ret)
>                         return ret;
>         }
>         fileio = q->fileio; // NULL pointer deference here
> ...
> }
>
> It was tested with vivi driver and qv4l2 for selecting read() as capture method.
> The OOPS happened when I've artificially forced the error by commenting the line:
>         if (fileio->bufs[i].vaddr == NULL)
>

... but if you manually changed the original source, how
can this be a real BUG?

Or am I missing something here ?

    Ezequiel
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