From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgg@ziepe.ca>
Subject: Re: [PATCH v2 2/3] test_overflow: Add shift overflow tests
Date: Tue, 31 Jul 2018 20:13:53 -0600
Message-ID: <20180801021353.GA31192@ziepe.ca>
References: <20180801000039.44314-1-keescook@chromium.org>
 <20180801000039.44314-3-keescook@chromium.org>
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In-Reply-To: <20180801000039.44314-3-keescook@chromium.org>
Sender: linux-kernel-owner@vger.kernel.org
To: Kees Cook <keescook@chromium.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>, Leon Romanovsky <leon@kernel.org>, Bart Van Assche <Bart.VanAssche@wdc.com>, Doug Ledford <dledford@redhat.com>, Dan Carpenter <dan.carpenter@oracle.com>, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
List-Id: linux-rdma@vger.kernel.org

On Tue, Jul 31, 2018 at 05:00:38PM -0700, Kees Cook wrote:
> +	/* Overflow: high bit falls off. */
> +	/* 10010110 */
> +	err |= TEST_ONE_SHIFT(150, 1, u8, 0, true);
> +	/* 1000100010010110 */
> +	err |= TEST_ONE_SHIFT(34966, 1, u16, 0, true);
> +	/* 10000100000010001000100010010110 */
> +	err |= TEST_ONE_SHIFT(2215151766U, 1, u32, 0, true);
> +	err |= TEST_ONE_SHIFT(2215151766U, 1, unsigned int, 0, true);
> +	/* 1000001000010000010000000100000010000100000010001000100010010110 */
> +	err |= TEST_ONE_SHIFT(9372061470395238550ULL, 1, u64, 0, true);

This same idea should be repeated with signed outputs and check both
overflow past the end (<<2) and overflow into the signed bit (<<1)

        /* Overflow, high bit falls into the sign bit or off the end */
	/* 01001011 */
	err |= TEST_ONE_SHIFT(75, 1, s8, 0, true);
	err |= TEST_ONE_SHIFT(75, 2, s8, 0, true);

And also general type mismatch overflow:

	err |= TEST_ONE_SHIFT(0x100, 0, u8, 0, true);
	err |= TEST_ONE_SHIFT(0xFF, 0, s8, 0, true);

Thanks,
Jason