From: Florian Westphal <fw@strlen.de>
To: Visa Hankala <visa@hankala.org>
Cc: Florian Westphal <fw@strlen.de>,
Steffen Klassert <steffen.klassert@secunet.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org
Subject: Re: [PATCH] xfrm: Fix wraparound in xfrm_policy_addr_delta()
Date: Tue, 29 Dec 2020 17:01:27 +0100 [thread overview]
Message-ID: <20201229160127.GA30823@breakpoint.cc> (raw)
In-Reply-To: <20201229145009.cGOUak0JdKIIgGAv@hankala.org>
Visa Hankala <visa@hankala.org> wrote:
> Use three-way comparison for address elements to avoid integer
> wraparound in the result of xfrm_policy_addr_delta().
>
> This ensures that the search trees are built and traversed correctly
> when the difference between compared address elements is larger
> than INT_MAX.
Please provide an update to tools/testing/selftests/net/xfrm_policy.sh
that shows that this is a problem.
> switch (family) {
> case AF_INET:
> - if (sizeof(long) == 4 && prefixlen == 0)
> - return ntohl(a->a4) - ntohl(b->a4);
> - return (ntohl(a->a4) & ((~0UL << (32 - prefixlen)))) -
> - (ntohl(b->a4) & ((~0UL << (32 - prefixlen))));
> + mask = ~0U << (32 - prefixlen);
> + ma = ntohl(a->a4) & mask;
> + mb = ntohl(b->a4) & mask;
This is suspicious. Is prefixlen == 0 impossible?
If not, then after patch
mask = ~0U << 32;
... and function returns 0.
next prev parent reply other threads:[~2020-12-29 16:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 14:58 [PATCH] xfrm: Fix wraparound in xfrm_policy_addr_delta() Visa Hankala
2020-12-29 16:01 ` Florian Westphal [this message]
2020-12-30 12:06 ` Visa Hankala
2020-12-30 12:46 ` Florian Westphal
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