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From: David Howells <dhowells@redhat.com>
In-Reply-To: <18425.1492778504@warthog.procyon.org.uk>
References: <18425.1492778504@warthog.procyon.org.uk> <a7d1fa79-b479-184e-af7e-b4319490f2a3@gmail.com>
Cc: dhowells@redhat.com,
        "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
        lkml <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>, hch@infradead.org
Subject: Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?]
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Date: Fri, 21 Apr 2017 13:47:20 +0100
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David Howells <dhowells@redhat.com> wrote:

> > Similarly, there appears to be no check for invalid flags in the
> > 'flags' argument of statx(). Why is there also not such a check
> > there?
> 
> Like this?
> 
> 	if (mask & STATX__RESERVED)
> 		return -EINVAL;

Sorry, I misread.  You referred to flags, not mask.  There's this in
sys_statx:

	if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
		return -EINVAL;

this in vfs_statx:

	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
		       AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
		return -EINVAL;

and this in vfs_statx_fd:

	if (query_flags & ~KSTAT_QUERY_FLAGS)
		return -EINVAL;

I don't necessarily agree with that last one, but other people think it should
be there.

David