From: Aristeu Rozanski <aris-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Cc: Fengguang Wu
<fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
kernel-janitors-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [cgroup:for-next 5/6] fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new_xattr'.
Date: Wed, 12 Sep 2012 09:40:32 -0400 [thread overview]
Message-ID: <20120912134031.GC19694@redhat.com> (raw)
In-Reply-To: <20120912075517.GZ19396@mwanda>
On Wed, Sep 12, 2012 at 10:55:17AM +0300, Dan Carpenter wrote:
> On Wed, Sep 12, 2012 at 10:28:13AM +0800, Fengguang Wu wrote:
> > Hi Aristeu,
> >
> > FYI, there are new smatch warnings show up in
> >
> > tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
> > head: 9814e970d7947dcc5ab7b37a53514c0098bfacc9
> > commit: 38f38657444d15e1a8574eae80ed3de9f501737a xattr: extract simple_xattr code from tmpfs
> >
> >
> > fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new_xattr'.
> >
>
> I don't know if this specific code is buggy or not. It would depend
> on how the function is called.
this should be safe. the only way to have value == NULL (thus keeping
new_xattr from being initialized) is if you call __simple_xattr_set()
directly with the intention of removing an existing entry.
> But potentially I should disable this Smatch rule. It tends to have
> a lot of false positives. The thing is that GCC complains if you
> don't initialize "new_xattr", but if you initialize it to NULL then
> Smatch complains.
>
> One solution might be to use the unitialized_var() macro.
>
> - struct simple_xattr *new_xattr = NULL;
> + struct simple_xattr *uninitialized_var(new_xattr);
>
> That would make both GCC and Smatch happy.
Sounds good to me. Will get a patch ready. Thanks Dan.
--
Aristeu
WARNING: multiple messages have this Message-ID (diff)
From: Aristeu Rozanski <aris@redhat.com>
To: kernel-janitors@vger.kernel.org
Subject: Re: [cgroup:for-next 5/6] fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new
Date: Wed, 12 Sep 2012 13:40:32 +0000 [thread overview]
Message-ID: <20120912134031.GC19694@redhat.com> (raw)
In-Reply-To: <20120912022813.GA17922@localhost>
On Wed, Sep 12, 2012 at 10:55:17AM +0300, Dan Carpenter wrote:
> On Wed, Sep 12, 2012 at 10:28:13AM +0800, Fengguang Wu wrote:
> > Hi Aristeu,
> >
> > FYI, there are new smatch warnings show up in
> >
> > tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
> > head: 9814e970d7947dcc5ab7b37a53514c0098bfacc9
> > commit: 38f38657444d15e1a8574eae80ed3de9f501737a xattr: extract simple_xattr code from tmpfs
> >
> >
> > fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new_xattr'.
> >
>
> I don't know if this specific code is buggy or not. It would depend
> on how the function is called.
this should be safe. the only way to have value = NULL (thus keeping
new_xattr from being initialized) is if you call __simple_xattr_set()
directly with the intention of removing an existing entry.
> But potentially I should disable this Smatch rule. It tends to have
> a lot of false positives. The thing is that GCC complains if you
> don't initialize "new_xattr", but if you initialize it to NULL then
> Smatch complains.
>
> One solution might be to use the unitialized_var() macro.
>
> - struct simple_xattr *new_xattr = NULL;
> + struct simple_xattr *uninitialized_var(new_xattr);
>
> That would make both GCC and Smatch happy.
Sounds good to me. Will get a patch ready. Thanks Dan.
--
Aristeu
next prev parent reply other threads:[~2012-09-12 13:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-12 2:28 [cgroup:for-next 5/6] fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new_xattr' Fengguang Wu
2012-09-12 2:28 ` [cgroup:for-next 5/6] fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new_xat Fengguang Wu
2012-09-12 7:55 ` [cgroup:for-next 5/6] fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new_xattr' Dan Carpenter
2012-09-12 7:55 ` [cgroup:for-next 5/6] fs/xattr.c:882 __simple_xattr_set() error: potential NULL dereference 'new Dan Carpenter
2012-09-12 13:40 ` Aristeu Rozanski [this message]
2012-09-12 13:40 ` Aristeu Rozanski
2012-09-12 14:31 ` [PATCH] xattr: mark variable as uninitialized to make both gcc and smatch happy Aristeu Rozanski
2012-09-12 14:31 ` Aristeu Rozanski
[not found] ` <20120912143112.GE19694-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-12 18:42 ` Tejun Heo
2012-09-12 18:42 ` Tejun Heo
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