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

[Adrian Bunk <bunk@stusta.de>]

On Wed, Mar 22, 2006 at 03:27:09PM -0800, Joel Becker wrote:
> On Thu, Mar 23, 2006 at 12:05:29AM +0100, Eric Sesterhenn wrote:
> > this fixes coverity bug #845, if group is NULL,
> > we dereference it when setting up dentry.
> 
> 	Is the converity checker merly looking at in-function patterns?
> Where can I access the bug report (sorry for the question).
> 	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.

Coverity is correct that something is wrong:

<--  snip  -->

...
        struct dentry *dentry = group->cg_item.ci_dentry;
        int ret = 0;
        int i;

        if (group && group->default_groups) {
...

<--  snip  -->

The question is only whether the dereferencing is a real bug or there's 
only the harmless issue of a superfluous check.

> Joel

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