From: Andrew Morton <akpm@linux-foundation.org>
To: Kees Cook <keescook@chromium.org>
Cc: Xiaotian Feng <xtfeng@gmail.com>,
linux-kernel@vger.kernel.org,
Xiaotian Feng <dannyfeng@tencent.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Vasiliy Kulikov <segoon@openwall.com>,
Stephen Wilson <wilsons@start.ca>,
David Rientjes <rientjes@google.com>
Subject: Re: [PATCH] proc: fix null pointer deref in proc_pid_permission()
Date: Wed, 11 Jan 2012 13:58:47 -0800 [thread overview]
Message-ID: <20120111135847.d28425c6.akpm@linux-foundation.org> (raw)
In-Reply-To: <20120111204330.GT2618@outflux.net>
On Wed, 11 Jan 2012 12:43:30 -0800
Kees Cook <keescook@chromium.org> wrote:
> Hi,
>
> On Wed, Jan 11, 2012 at 01:47:05PM -0500, Xiaotian Feng wrote:
> > get_proc_task() can fail to search the task and return NULL, put_task_struct()
> > will then bomb the kernel with following oops:
> >
> > [ 1870.574045] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> > [ 1870.574065] IP: [<ffffffff81217d34>] proc_pid_permission+0x64/0xe0
> > [ 1870.574088] PGD 112075067 PUD 112814067 PMD 0
> > [ 1870.574106] Oops: 0002 [#1] PREEMPT SMP
> >
> > This is a regression introduced by commit 0499680a, kernel should
> > return -ESRCH if get_proc_task() failed.
>
> Nice catch!
>
> However since this error is returned to userspace, shouldn't this be
> -ENOENT instead?
>
Failed get_proc_task() frequently results in -ESRCH. And less
frequently results in -ENOENT.
It seems odd that inode_operations.permission() would ever return
anything other than zero or -EPERM.
next prev parent reply other threads:[~2012-01-11 21:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-11 18:47 [PATCH] proc: fix null pointer deref in proc_pid_permission() Xiaotian Feng
2012-01-11 20:43 ` Kees Cook
2012-01-11 21:58 ` Andrew Morton [this message]
2012-01-11 22:41 ` Kees Cook
2012-01-12 2:45 ` Xiaotian Feng
2012-01-12 3:05 ` Andrew Morton
2012-01-11 21:49 ` David Rientjes
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