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From:   Paul Durrant <pdurrant@gmail.com>
Date:   Thu, 9 Jan 2020 13:36:22 +0000
Message-ID: <CACCGGhCGcdEq7CC3J0201ETvAd+PZ2fTDNUS3mo599Tuf-61yA@mail.gmail.com>
Subject: Re: [PATCH v1 4/4] xen/netback: Fix grant copy across page boundary
 with KASAN
To:     Sergey Dyasli <sergey.dyasli@citrix.com>
Cc:     xen-devel@lists.xen.org, kasan-dev@googlegroups.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        George Dunlap <george.dunlap@citrix.com>,
        Ross Lagerwall <ross.lagerwall@citrix.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Wei Liu <wei.liu@kernel.org>
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On Wed, 8 Jan 2020 at 15:21, Sergey Dyasli <sergey.dyasli@citrix.com> wrote:
>
> From: Ross Lagerwall <ross.lagerwall@citrix.com>
>
> When KASAN (or SLUB_DEBUG) is turned on, the normal expectation that
> allocations are aligned to the next power of 2 of the size does not
> hold. Therefore, handle grant copies that cross page boundaries.
>
> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
> ---
> RFC --> v1:
> - Added BUILD_BUG_ON to the netback patch
> - xenvif_idx_release() now located outside the loop
>
> CC: Wei Liu <wei.liu@kernel.org>
> CC: Paul Durrant <paul@xen.org>
[snip]
>
> +static void __init __maybe_unused build_assertions(void)
> +{
> +       BUILD_BUG_ON(sizeof(struct xenvif_tx_cb) > 48);

FIELD_SIZEOF(struct sk_buff, cb) rather than a magic '48' I think.

  Paul

> +}
> +
>  MODULE_LICENSE("Dual BSD/GPL");
>  MODULE_ALIAS("xen-backend:vif");
> --
> 2.17.1
>