Message-ID: <1501073531.1196.7.camel@gmail.com>
Subject: Re: [PATCH] fortify: Use WARN instead of BUG for now
From: Daniel Micay <danielmicay@gmail.com>
To: Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Al Viro <viro@zeniv.linux.org.uk>, David Howells <dhowells@redhat.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-kernel@vger.kernel.org
Date: Wed, 26 Jul 2017 08:52:11 -0400
In-Reply-To: <20170726035036.GA76341@beast>
References: <20170726035036.GA76341@beast>
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It should just be renamed from fortify_panic -> fortify_error, including
in arch/x86/boot/compressed/misc.c and arch/x86/boot/compressed/misc.c.
It can use WARN instead of BUG by with a 'default n', !COMPILE_TEST
option to use BUG again. Otherwise it needs to be patched downstream
when that's wanted.

I don't think splitting it is the right approach to improving the
runtime error handling. That only makes sense for the compile-time
errors due to the limitations of __attribute__((error)). Can we think
about that before changing it? Just make it use WARN for now.

The best debugging experience would be passing along the sizes and
having the fortify_error function convert that into nice error messages.
For memcpy(p, q, n), n can be larger than both the detected sizes of p
and q, not just either one. The error should just be saying the function
name and printing the copy size and maximum sizes of p and q. That's
going to increase the code size too but I think splitting it will be
worse and it goes in the wrong direction in terms of complexity. It's
going to make future extensions / optimization harder if it's split.