linux-kernel - Re: [PATCH V10] fixup: audit: implement audit by executable

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Date:	Mon, 10 Aug 2015 13:29:43 -0400
From:	Richard Guy Briggs <rgb@...hat.com>
To:	Paul Moore <pmoore@...hat.com>
Cc:	linux-audit@...hat.com, linux-kernel@...r.kernel.org,
	sgrubb@...hat.com, eparis@...hat.com, peter@...3.com
Subject: Re: [PATCH V10] fixup: audit: implement audit by executable

On 15/08/10, Paul Moore wrote:
> On Saturday, August 08, 2015 10:20:25 AM Richard Guy Briggs wrote:
> > diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
> > index 1255dbf..656c7e9 100644
> > --- a/kernel/audit_watch.c
> > +++ b/kernel/audit_watch.c
> > @@ -540,8 +540,14 @@ int audit_dupe_exe(struct audit_krule *new, struct
> > audit_krule *old)
> > 
> >  int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark
> > *mark) {
> > -	unsigned long ino = tsk->mm->exe_file->f_inode->i_ino;
> > -	dev_t dev = tsk->mm->exe_file->f_inode->i_sb->s_dev;
> > -
> > +	struct file *exe_file;
> > +	unsigned long ino;
> > +	dev_t dev;
> > +
> > +	rcu_read_lock();
> > +	exe_file = rcu_dereference(tsk->mm->exe_file);
> 
> This line is triggering a sparse error on my system:
> 
>  # make C=1 M=kernel
>  ...
>    CHECK   kernel/audit_watch.c
>  kernel/audit_watch.c:548:20: error: incompatible types in comparison  
>  expression (different address spaces)

That's odd.  I got this complaint when I had forgotten to add the
rcu_dereference() call, but not in its current state.  Mind you, I get
swamped with errors and warnings from all over the system (starting with
ptrace.c, signal.c, exit.c, fork.c, audit.c, ftrace.c,
selinux/netnode.c, ...) when I add
"M=kernel" to my build command, so I start to wonder how valid that
result is or that flag.  Where is M=kernel documented?

> For the record I'm using gcc v4.9.3 and sparse v0.5.0.

gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-11)
sparse 0.4.4-7.el6

> > +	ino = exe_file->f_inode->i_ino;
> > +	dev = exe_file->f_inode->i_sb->s_dev;
> > +	rcu_read_unlock();
> >  	return audit_mark_compare(mark, ino, dev);
> >  }
> 
> -- 
> paul moore
> security @ redhat
> 

- RGB

--
Richard Guy Briggs <rbriggs@...hat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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