linux-kernel - Re: [PATCH RESEND] pstore: fix NULL pointer dereference in console writes

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Message-ID: <20121115024946.GA12232@lizard>
Date:	Wed, 14 Nov 2012 18:49:46 -0800
From:	Anton Vorontsov <cbouatmailru@...il.com>
To:	Colin King <colin.king@...onical.com>
Cc:	Colin Cross <ccross@...roid.com>, Tony Luck <tony.luck@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] pstore: fix NULL pointer dereference in console
 writes

On Wed, Nov 14, 2012 at 11:49:53AM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Passing a NULL id causes a NULL pointer deference in writers
> such as erst_writer and efi_pstore_write because they expect
> to update this id.  Pass a dummy id instead.
> 
> This avoids a cascade of oopses caused when the initial
> pstore_console_write passes a null which in turn causes
> writes to the console causing further oopses in subsequent
> pstore_console_write calls.
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> Acked-by: Kees Cook <keescook@...omium.org>
> ---

Ugh. Thanks for the reminder, I completely forgot that I had this bit for
v3.7.

Applied, thanks! (I also added Cc: stable.)

>  fs/pstore/platform.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index a40da07..947fbe0 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -161,6 +161,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
>  
>  	while (s < e) {
>  		unsigned long flags;
> +		u64 id;
>  
>  		if (c > psinfo->bufsize)
>  			c = psinfo->bufsize;
> @@ -172,7 +173,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
>  			spin_lock_irqsave(&psinfo->buf_lock, flags);
>  		}
>  		memcpy(psinfo->buf, s, c);
> -		psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
> +		psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, c, psinfo);
>  		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
>  		s += c;
>  		c = e - s;
> -- 
> 1.7.10.4
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