netdev - Re: [net PATCH] bpf: devmap fix arithmetic overflow in bitmap

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Date:   Sun, 22 Oct 2017 00:54:41 +0100 (WEST)
From:   David Miller <davem@...emloft.net>
To:     john.r.fastabend@...il.com
Cc:     richard@....at, alexei.starovoitov@...il.com,
        netdev@...r.kernel.org, borkmann@...earbox.net
Subject: Re: [net PATCH] bpf: devmap fix arithmetic overflow in bitmap_size
 calculation

From: John Fastabend <john.r.fastabend@...il.com>
Date: Thu, 19 Oct 2017 09:03:52 -0700

> An integer overflow is possible in dev_map_bitmap_size() when
> calculating the BITS_TO_LONG logic which becomes, after macro
> replacement,
> 
> 	(((n) + (d) - 1)/ (d))
> 
> where 'n' is a __u32 and 'd' is (8 * sizeof(long)). To avoid
> overflow cast to u64 before arithmetic.
> 
> Reported-by: Richard Weinberger <richard@....at>
> Acked-by: Daniel Borkmann <daniel@...earbox.net>
> Signed-off-by: John Fastabend <john.fastabend@...il.com>

Applied.