[PATCH] pSeries hvsi char driver null pointer deref

[Hollis Blanchard]

On Thu, 2006-08-03 at 15:13 -0500, Linas Vepstas wrote:
> Andrew, 
> Please apply.
> 
> Under certain rare circumstances, it appears that there can be
> be a NULL-pointer deref when a user fiddles with terminal
> emeulation programs while outpu is being sent to the console.
> This patch checks for and avoids a NULL-pointer deref.
> 
> Signed-off-by: Hollis Blanchard <hollisbl at austin.ibm.com>
> Signed-off-by: Linas Vepstas <linas at austin.ibm.com>

That email address is incorrect.

Signed-off-by: Hollis Blanchard <hollisb at us.ibm.com>

> ----
>  drivers/char/hvsi.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.18-rc3-git1/drivers/char/hvsi.c
> ===================================================================
> --- linux-2.6.18-rc3-git1.orig/drivers/char/hvsi.c	2006-08-03 14:50:00.000000000 -0500
> +++ linux-2.6.18-rc3-git1/drivers/char/hvsi.c	2006-08-03 14:51:46.000000000 -0500
> @@ -311,7 +311,8 @@ static void hvsi_recv_control(struct hvs
>  				/* CD went away; no more connection */
>  				pr_debug("hvsi%i: CD dropped\n", hp->index);
>  				hp->mctrl &= TIOCM_CD;
> -				if (!(hp->tty->flags & CLOCAL))
> +				/* If userland hasn't done an open(2) yet, hp->tty is NULL. */
> +				if (hp->tty && !(hp->tty->flags & CLOCAL))
>  					*to_hangup = hp->tty;
>  			}
>  			break;
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