From: Ralf Baechle <ralf@linux-mips.org>
To: Chad Reese <creese@caviumnetworks.com.redhat.com>
Cc: linux-mips@linux-mips.org
Subject: Re: 64bit kernel/N32 userspace - shmctl corrupts userspace memory
Date: Tue, 25 Jul 2006 22:07:20 -0400 [thread overview]
Message-ID: <20060726020720.GB21024@linux-mips.org> (raw)
In-Reply-To: <44C6B829.8050508@caviumnetworks.com>
On Tue, Jul 25, 2006 at 05:32:41PM -0700, Chad Reese wrote:
> If you're running a 64bit kernel with N32 userspace, shmctl will corrupt
> memory in userspace. When copy_shmid_to_user() is called, it copies the
> entire kernel shmid_ds into userspace. For a 64bit kernel, this is 88
> bytes. In N32 userspace it is 76 bytes.
>
> My hack to get around the problem is attached, but I expect someone here
> will be able to come up with a better fix. shmid_ds contains a lot of
> members that are marked unused. Are these really useless?
They need to be there for compatibility with older revisions of the
structure - we can increase the size of the structure but not decrease.
Talking about compatibility, you change breaks N64 compatibility ...
Ralf
prev parent reply other threads:[~2006-07-26 2:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-26 0:32 64bit kernel/N32 userspace - shmctl corrupts userspace memory Chad Reese
2006-07-26 2:04 ` Ralf Baechle
2006-07-26 2:30 ` Chad Reese
2006-07-26 3:13 ` Atsushi Nemoto
2006-07-26 2:07 ` Ralf Baechle [this message]
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