From: Jeff Layton <jlayton@poochiereds.net>
To: Vitaly Osipov <vitaly.osipov@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
linux-sparse@vger.kernel.org,
Jeff Layton <jlayton@primarydata.com>
Subject: Re: [PATCH][RFC] err.h: silence sparse warning: dereference of noderef expression
Date: Fri, 13 Jun 2014 08:05:37 -0400 [thread overview]
Message-ID: <20140613080537.75635d81@f20.localdomain> (raw)
In-Reply-To: <CAH42NiXUE70oVnZJNhkvgKT5FSfnMVOBEWau84E9YAbufBDHMw@mail.gmail.com>
On Thu, 12 Jun 2014 18:06:25 +1000
Vitaly Osipov <vitaly.osipov@gmail.com> wrote:
> Nothing shows up for me on x86_64, allmodconfig, linux-next from 10 of
> June. My sparse has been compiled from sources.
>
> $ make fs/locks.o C=2 CHECK="/home/vosipov/bin/sparse"
> CHK include/config/kernel.release
> CHK include/generated/uapi/linux/version.h
> CHK include/generated/utsrelease.h
> CALL scripts/checksyscalls.sh
> CHECK scripts/mod/empty.c
> CHECK fs/locks.c
>
> $ sparse —version
> v0.5.0
>
> $ which sparse
> /home/vosipov/bin/sparse
>
> Regards,
> Vitaly
>
>
> On Wed, Jun 11, 2014 at 11:51 PM, Jeff Layton <jlayton@poochiereds.net> wrote:
> > On Wed, 11 Jun 2014 16:11:46 +0300
> > Dan Carpenter <dan.carpenter@oracle.com> wrote:
> >
> >> On Wed, Jun 11, 2014 at 07:06:32AM -0400, Jeff Layton wrote:
> >> > $ rpm -q sparse
> >> > sparse-0.5.0-1.fc20.x86_64
> >> >
> >> > I see it all over the tree, but an easy example is fs/locks.c:
> >> >
> >> > $ make fs/locks.o C=1
> >> > make[1]: Nothing to be done for `all'.
> >> > make[1]: Nothing to be done for `relocs'.
> >> > CHK include/config/kernel.release
> >> > CHK include/generated/uapi/linux/version.h
> >> > CHK include/generated/utsrelease.h
> >> > CALL scripts/checksyscalls.sh
> >> > CHECK fs/locks.c
> >> > include/linux/err.h:35:16: warning: dereference of noderef expression
> >> > include/linux/err.h:30:23: warning: dereference of noderef expression
> >> > include/linux/err.h:35:16: warning: dereference of noderef expression
> >> > include/linux/err.h:30:23: warning: dereference of noderef expression
> >> > CC fs/locks.o
> >> >
> >> > It has two IS_ERR calls and two PTR_ERR calls, and each generates the
> >> > warning.
> >> >
> >>
> >> I downloaded the Fedora SRPM and built the binary but I still wasn't
> >> able to reproduce the bug.
> >>
> >> dcarpenter@speke:~/progs/kernel/devel$ /tmp/sparse/sparse-0.5.0/sparse --version
> >> 0.5.0
> >> dcarpenter@speke:~/progs/kernel/devel$ make C=2 CHECK=/tmp/sparse/sparse-0.5.0/sparse fs/locks.o
> >> CHK include/config/kernel.release
> >> CHK include/generated/uapi/linux/version.h
> >> CHK include/generated/utsrelease.h
> >> CALL scripts/checksyscalls.sh
> >> <stdin>:1226:2: warning: #warning syscall finit_module not implemented [-Wcpp]
> >> <stdin>:1229:2: warning: #warning syscall sched_setattr not implemented [-Wcpp]
> >> <stdin>:1232:2: warning: #warning syscall sched_getattr not implemented [-Wcpp]
> >> <stdin>:1235:2: warning: #warning syscall renameat2 not implemented [-Wcpp]
> >> CHECK scripts/mod/empty.c
> >> CHECK fs/locks.c
> >> dcarpenter@speke:~/progs/kernel/devel$
> >>
> >> I'm on today's linux-next. I can't think of a kernel configuration
> >> issue which would cause this...
> >>
> >> regards,
> >> dan carpenter
> >
> > Could it be arch-specific then? What arch are you using? I'm on x86_64.
> > I know that quite a few other people have mentioned seeing these
> > warnings as well, so I'm pretty sure it's not just me.
> >
Ha! It turns out that my hand-built sparse also works fine, so the
problem seems to be in the Fedora package.
With a little trial-and-error, I figured out what's causing the
problem, but I'm a little baffled as to why it's occurring.
The Fedora SRPM builds the program with -fpic. When I remove that flag,
this problem goes away. I'd appreciate any insight into why that would
break things. I doubt PIC really makes much difference security-wise in
sparse, so removing it shouldn't matter much, but I wonder if this
indicates an underlying bug in sparse itself?
I'll do a bit more investigation, but I should be able to get a fixed
package pushed into Fedora soon. Thanks for the help, and obviously the
RFC patch I originally "proposed" can be dropped.
--
Jeff Layton <jlayton@poochiereds.net>
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next prev parent reply other threads:[~2014-06-13 12:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-10 21:38 [PATCH][RFC] err.h: silence sparse warning: dereference of noderef expression Jeff Layton
2014-06-11 5:45 ` Dan Carpenter
2014-06-11 11:06 ` Jeff Layton
2014-06-11 13:11 ` Dan Carpenter
2014-06-11 13:51 ` Jeff Layton
2014-06-12 8:06 ` Vitaly Osipov
2014-06-13 12:05 ` Jeff Layton [this message]
2014-06-13 15:56 ` Josh Triplett
2014-06-14 13:44 ` Jeff Layton
2014-06-14 14:05 ` Vitaly Osipov
2014-06-14 16:47 ` Jeff Layton
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