From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Vishwanath Pai <vpai@akamai.com>
Cc: netfilter-devel@vger.kernel.org, torvalds@linux-foundation.org,
davem@davemloft.net, kadlec@blackhole.kfki.hu, johunt@akamai.com,
fw@strlen.de, netdev@vger.kernel.org, pai.vishwain@gmail.com,
mingo@kernel.org, ilubashe@akamai.com, bp@alien8.de,
luto@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org,
brgerst@gmail.com, andrew.cooper3@citrix.com, jgross@suse.com,
boris.ostrovsky@oracle.com, keescook@chromium.org,
akpm@linux-foundation.org, arnd@arndb.de
Subject: Re: [PATCH v2] netfilter: xt_hashlimit: fix build error caused by 64bit division
Date: Fri, 8 Sep 2017 14:56:35 +0200 [thread overview]
Message-ID: <20170908125635.GA27811@salvia> (raw)
In-Reply-To: <1504849138-17427-1-git-send-email-vpai@akamai.com>
On Fri, Sep 08, 2017 at 01:38:58AM -0400, Vishwanath Pai wrote:
> 64bit division causes build/link errors on 32bit architectures. It
> prints out error messages like:
>
> ERROR: "__aeabi_uldivmod" [net/netfilter/xt_hashlimit.ko] undefined!
>
> The value of avg passed through by userspace in BYTE mode cannot exceed
> U32_MAX. Which means 64bit division in user2rate_bytes is unnecessary.
> To fix this I have changed the type of param 'user' to u32.
>
> Since anything greater than U32_MAX is an invalid input we error out in
> hashlimit_mt_check_common() when this is the case.
>
> Changes in v2:
> Making return type as u32 would cause an overflow for small
> values of 'user' (for example 2, 3 etc). To avoid this I bumped up
> 'r' to u64 again as well as the return type. This is OK since the
> variable that stores the result is u64. We still avoid 64bit
> division here since 'user' is u32.
Applied, thanks.
prev parent reply other threads:[~2017-09-08 12:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-08 5:38 [PATCH v2] netfilter: xt_hashlimit: fix build error caused by 64bit division Vishwanath Pai
2017-09-08 12:56 ` Pablo Neira Ayuso [this message]
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