netdev - Re: [PATCH v1 net 3/3] selftest: net: Check wraparounds for sk->sk_rmem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250324182602.47871-1-kuniyu@amazon.com>
Date: Mon, 24 Mar 2025 11:25:20 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <willemdebruijn.kernel@...il.com>
CC: <davem@...emloft.net>, <dsahern@...nel.org>, <edumazet@...gle.com>,
	<horms@...nel.org>, <kuba@...nel.org>, <kuni1840@...il.com>,
	<kuniyu@...zon.com>, <netdev@...r.kernel.org>, <pabeni@...hat.com>
Subject: Re: [PATCH v1 net 3/3] selftest: net: Check wraparounds for sk->sk_rmem_alloc.

From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Date: Mon, 24 Mar 2025 11:58:06 -0400
> > +TEST_F(so_rcvbuf, rmem_max)
> > +{
> > +	char buf[16] = {};
> > +	int ret, i;
> > +
> > +	create_socketpair(_metadata, self, variant);
> > +
> > +	ret = setsockopt(self->server, SOL_SOCKET, SO_RCVBUFFORCE,
> > +			 &(int){INT_MAX}, sizeof(int));
> > +	ASSERT_EQ(ret, 0);
> > +
> > +	ASSERT_EQ(get_prot_pages(_metadata, variant), 0);
> > +
> > +	for (i = 1; ; i++) {
> > +		ret = send(self->client, buf, sizeof(buf), 0);
> > +		ASSERT_EQ(ret, sizeof(buf));
> > +
> > +		if (i % 10000 == 0) {
> > +			int pages = get_prot_pages(_metadata, variant);
> > +
> > +			/* sk_rmem_alloc wrapped around too much ? */
> > +			ASSERT_LE(pages, *variant->max_pages);
> > +
> > +			if (pages == *variant->max_pages)
> > +				break;
> 
> Does correctness depend here on max_pages being a multiple of 10K?

10K may be too conservative, but at least we need to ensure
that the size of accumulated skbs exceeds 1 PAGE_SIZE to
fail on the ASSERT_LE(), otherwise we can't detect the multiple
wraparounds even without patch 1.

The later sleep for call_rcu() was dominant than this loop on
my machine.

Thanks!