From: Marcin Slusarz <marcin.slusarz@gmail.com>
To: Johannes Weiner <hannes@saeurebad.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@ZenIV.linux.org.uk>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 6/6] ERR_PTR: warn when ERR_PTR parameter is not errno value
Date: Thu, 22 May 2008 18:08:53 +0200 [thread overview]
Message-ID: <20080522160851.GC8447@joi> (raw)
In-Reply-To: <8763tav6hi.fsf@saeurebad.de>
On Mon, May 19, 2008 at 02:11:21PM +0200, Johannes Weiner wrote:
> Hi,
>
> Alexey Dobriyan <adobriyan@gmail.com> writes:
>
> > On Mon, May 19, 2008 at 01:13:20AM +0200, Johannes Weiner wrote:
> >> Marcin Slusarz <marcin.slusarz@gmail.com> writes:
> >>
> >> > Check at runtime whether error argument of ERR_PTR and ERR_OR_0_PTR
> >> > is valid. It can catch bugs which possibly lead to oops or panic earlier.
> >> >
> >> > Currently there are > 600 calls of ERR_PTR with non-constant argument
> >> > in Linux kernel sources.
> >
> >> > --- a/include/linux/err.h
> >> > +++ b/include/linux/err.h
> >> > @@ -3,6 +3,7 @@
> >> >
> >> > #include <linux/compiler.h>
> >> >
> >> > +#include <asm/bug.h>
> >> > #include <asm/errno.h>
> >> >
> >> > /*
> >> > @@ -21,6 +22,7 @@
> >> >
> >> > static inline void *__ERR_PTR(long error)
> >> > {
> >> > + WARN_ON(!IS_ERR_VALUE(error));
> >> > return (void *) error;
> >> > }
> >> >
> >> > @@ -28,6 +30,7 @@ static inline void *__ERR_PTR(long error)
> >> >
> >> > static inline void *__ERR_OR_0_PTR(long error)
> >> > {
> >> > + WARN_ON(!IS_ERR_VALUE(error) && error);
> >> > return (void *) error;
> >> > }
> >>
> >> How about WARN_ON_ONCE() instead? That would warn once for each erroneous user
> >> which should be enough.
> >
> > And blow up .bss ?
>
> Well, okay. Perhaps ratelimiting? I really prefer a bigger image size
> over a spammed dmesg.
Well, when I add 0 as a valid argument for ERR_PTR, this check won't add too many
false positives, so I think simple WARN_ON is safe.
Marcin
prev parent reply other threads:[~2008-05-22 16:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-11 20:12 [PATCH] let ERR_PTR BUILD_BUG_ON when we know its argument is not a valid errno Marcin Slusarz
2008-05-12 23:38 ` Andrew Morton
2008-05-13 20:18 ` Marcin Slusarz
2008-05-18 21:56 ` [PATCH 0/6] Sanity checks for ERR_PTR argument Marcin Slusarz
2008-05-18 21:56 ` [PATCH 1/6] ERR_PTR: if errno value is known at compile time, make sure it's valid Marcin Slusarz
2008-05-19 6:38 ` Alexey Dobriyan
2008-05-22 16:03 ` Marcin Slusarz
2008-05-18 22:01 ` [PATCH 2/6] ERR_PTR: add ERR_OR_0_PTR Marcin Slusarz
2008-05-18 23:04 ` Johannes Weiner
2008-05-19 5:55 ` Christoph Hellwig
2008-05-19 6:33 ` Al Viro
2008-05-18 22:01 ` [PATCH 3/6] vfs: open_exec cleanup Marcin Slusarz
2008-05-19 5:53 ` Christoph Hellwig
2008-05-22 15:57 ` Marcin Slusarz
2008-05-18 22:03 ` [PATCH 4/6] procfs: switch ERR_PTR to ERR_OR_0_PTR when "error" might be 0 Marcin Slusarz
2008-05-18 22:03 ` [PATCH 5/6] vfs: fix ERR_PTR abuse in generic_readlink Marcin Slusarz
2008-05-18 22:04 ` [PATCH 6/6] ERR_PTR: warn when ERR_PTR parameter is not errno value Marcin Slusarz
2008-05-18 23:13 ` Johannes Weiner
2008-05-19 6:43 ` Alexey Dobriyan
2008-05-19 12:11 ` Johannes Weiner
2008-05-22 16:08 ` Marcin Slusarz [this message]
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