linux-kernel - Re: [PATCH] UBI: Fix crash in try_recover

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Date:   Thu, 13 Oct 2016 16:24:58 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Richard Weinberger <richard@....at>,
        Brian Norris <computersforpeace@...il.com>,
        Artem Bityutskiy <dedekind1@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] UBI: Fix crash in try_recover_peb()

Hi Geert,

On Thu, 13 Oct 2016 16:05:36 +0200
Geert Uytterhoeven <geert@...ux-m68k.org> wrote:

>     drivers/mtd/ubi/eba.c: In function ‘try_recover_peb’:
>     drivers/mtd/ubi/eba.c:744: warning: ‘vid_hdr’ is used uninitialized in this function
> 
> The pointer vid_hdr is indeed not initialized, leading to a crash when
> it is dereferenced.
> 
> Fix this by obtaining the pointer from the VID buffer, like is done
> everywhere else.

Indeed, I don't know how I missed that one :-/.

> 
> Fixes: 3291b52f9ff0acc8 ("UBI: introduce the VID buffer concept")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>

One minor comment below, otherwise

Reviewed-by: Boris Brezillon <boris.brezillon@...e-electrons.com>

> ---
> Completely untested. And I know nothing about UBI ;-)
> ---
>  drivers/mtd/ubi/eba.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
> index 95c4048a371e87b6..388e46be6ad92805 100644
> --- a/drivers/mtd/ubi/eba.c
> +++ b/drivers/mtd/ubi/eba.c
> @@ -741,6 +741,7 @@ static int try_recover_peb(struct ubi_volume *vol, int pnum, int lnum,
>  		goto out_put;
>  	}
>  
> +	vid_hdr = ubi_get_vid_hdr(vidb);

Can you move this assignment at variable declaration time?

>  	ubi_assert(vid_hdr->vol_type == UBI_VID_DYNAMIC);
>  
>  	mutex_lock(&ubi->buf_mutex);