Re: [Patch] Possible NULL pointer dereference in fs/configfs/dir.c

[Adrian Bunk]

On Thu, Mar 23, 2006 at 12:36:54AM +0100, Eric Sesterhenn wrote:
>...
> On Wed, 2006-03-22 at 15:27 -0800, Joel Becker wrote:
>...
> > 	group cannot be null here, we aren't called any other way.  So
> > while you are correct that the code below is needed in the presence of a
> > NULL group, really the "if (group" isn't necessary, just the "if
> > (group->default_groups)".  I could even BUG_ON() if you'd like.
> 
> I would then propose the following patch, so the check can be
> removed for people who like small kernels. I dont think gcc notices
> that all callers use non-NULL values and optimizes it away.
> 
> --- linux-2.6.16/fs/configfs/dir.c.orig	2006-03-23 00:31:16.000000000 +0100
> +++ linux-2.6.16/fs/configfs/dir.c	2006-03-23 00:32:07.000000000 +0100
> @@ -504,7 +504,9 @@ static int populate_groups(struct config
>  	int ret = 0;
>  	int i;
>  
> -	if (group && group->default_groups) {
> +	BUG_ON(!group);		/* group == NULL is not allowed */
> +	
> +	if (group->default_groups) {
>...

Why do we need a BUG_ON() if we already got an Oops?
Simply remove the check.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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