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Date:   Tue, 12 Feb 2019 20:38:09 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     demiobenour@gmail.com
Cc:     "open list:FILESYSTEMS (VFS and infrastructure)" 
        <linux-fsdevel@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] Return -EINVAL if userspace passes bogus flags to
 open()
Message-ID: <20190212203809.GK2217@ZenIV.linux.org.uk>
References: <20190212145450.2200-1-demiobenour@gmail.com>
 <20190212145450.2200-4-demiobenour@gmail.com>
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On Tue, Feb 12, 2019 at 09:54:47AM -0500, demiobenour@gmail.com wrote:
> From: "Demi M. Obenour" <demiobenour@gmail.com>
> 
> While testing the O_PATHSTATIC patch, I discovered that Linux does not
> return any error if an invalid flag is passed to open(2).  This prevents
> adding new flags without a (minor) risk of breaking userspace.
> Therefore, add a check for invalid flags, and return -EINVAL if any are
> found.

... which would qualtify as userland ABI breakage all by itself.