From: Rob Browning <rlb@defaultvalue.org>
To: Christoph Hellwig <hch@infradead.org>,
Aurelien Jarno <aurelien@aurel32.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org,
Robert Edmonds <edmonds@debian.org>,
daryl5@arcor.de
Subject: Re: Argument type for FS_IOC_GETFLAGS/FS_IOC_SETFLAGS ioctls
Date: Mon, 30 Jun 2014 17:51:08 -0500 [thread overview]
Message-ID: <87simm2eqr.fsf@trouble.defaultvalue.org> (raw)
In-Reply-To: <20131127101536.GA24697@infradead.org>
Christoph Hellwig <hch@infradead.org> writes:
> The problem is that as you indeed pointed out the ABI is that an int
> needs to be passed. The _IOR/_IOW generate a ioctl number based on
> a few inputs including the type of the argument, which is just
> passed to sizeof. So the supposedly self-documenting ioctl defintions
> disagree with the actual ABI.
>
> There's nothing that can be fixed in the kernel except for better
> documenting the actual ABI, and why the ioctl defintion is very misleading
> in this case.
>
> The userspace programs that were mislead by this will need to fixed.
So we haven't delved deeply yet, but here's a presumably little-endian,
64-bit system where using an int with FS_IOC_GETFLAGS appears to corrupt
the stack:
https://groups.google.com/d/msg/bup-list/y4CW6Ib7XUk/sCy7AUHhiKYJ
and here's the relevant call:
https://github.com/bup/bup/blob/0e0b5324699342601ce1b9a97c0a2e1faf6fe7ff/lib/bup/_helpers.c#L830
--
Rob Browning
rlb @defaultvalue.org and @debian.org
GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A
GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
prev parent reply other threads:[~2014-06-30 22:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-26 20:05 Argument type for FS_IOC_GETFLAGS/FS_IOC_SETFLAGS ioctls Aurelien Jarno
2013-11-27 1:01 ` Darrick J. Wong
2013-11-27 4:00 ` Theodore Ts'o
2013-11-27 10:03 ` Aurelien Jarno
2013-11-27 13:34 ` Theodore Ts'o
2013-11-27 18:14 ` Robert Edmonds
2013-11-27 23:14 ` Aurelien Jarno
2013-11-29 0:53 ` Andreas Dilger
2013-11-29 4:54 ` Theodore Ts'o
2013-11-29 5:27 ` Dave Chinner
2013-11-29 14:22 ` Theodore Ts'o
2013-11-29 16:32 ` Rob Browning
2013-12-01 22:20 ` Dave Chinner
2013-12-02 4:52 ` Theodore Ts'o
2013-12-02 22:30 ` Dave Chinner
2013-11-29 21:55 ` Andreas Dilger
2013-12-19 18:20 ` Rob Browning
2013-12-19 23:30 ` Darrick J. Wong
2013-11-27 10:15 ` Christoph Hellwig
2014-06-30 22:51 ` Rob Browning [this message]
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