From: Kees Cook <keescook@chromium.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, netdev <netdev@vger.kernel.org>,
Coco Li <lixiaoyan@google.com>, Tariq Toukan <tariqt@nvidia.com>,
Saeed Mahameed <saeedm@nvidia.com>,
Leon Romanovsky <leon@kernel.org>
Subject: Re: [PATCH v4 net-next 12/12] mlx5: support BIG TCP packets
Date: Sat, 7 May 2022 00:46:17 -0700 [thread overview]
Message-ID: <202205070026.11B94DF@keescook> (raw)
In-Reply-To: <20220506185405.527a79d4@kernel.org>
On Fri, May 06, 2022 at 06:54:05PM -0700, Jakub Kicinski wrote:
> On Fri, 6 May 2022 17:32:43 -0700 Eric Dumazet wrote:
> > On Fri, May 6, 2022 at 3:34 PM Jakub Kicinski <kuba@kernel.org> wrote:
> > > In function ‘fortify_memcpy_chk’,
> > > inlined from ‘mlx5e_sq_xmit_wqe’ at ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:408:5:
> > > ../include/linux/fortify-string.h:328:25: warning: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
> > > 328 | __write_overflow_field(p_size_field, size);
> > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ah, my old friend, inline_hdr.start. Looks a lot like another one I fixed
earlier in ad5185735f7d ("net/mlx5e: Avoid field-overflowing memcpy()"):
if (attr->ihs) {
if (skb_vlan_tag_present(skb)) {
eseg->inline_hdr.sz |= cpu_to_be16(attr->ihs + VLAN_HLEN);
mlx5e_insert_vlan(eseg->inline_hdr.start, skb, attr->ihs);
stats->added_vlan_packets++;
} else {
eseg->inline_hdr.sz |= cpu_to_be16(attr->ihs);
memcpy(eseg->inline_hdr.start, skb->data, attr->ihs);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}
dseg += wqe_attr->ds_cnt_inl;
This is actually two regions, 2 bytes in eseg and everything else in
dseg. Splitting the memcpy() will work:
memcpy(eseg->inline_hdr.start, skb->data, sizeof(eseg->inline_hdr.start));
memcpy(dseg, skb->data + sizeof(eseg->inline_hdr.start), ihs - sizeof(eseg->inline_hdr.start));
But this begs the question, what is validating that ihs -2 is equal to
wqe_attr->ds_cnt_inl * sizeof(*desg) ?
And how is wqe bounds checked?
> > > In function ‘fortify_memcpy_chk’,
> > > inlined from ‘mlx5i_sq_xmit’ at ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:962:4:
> > > ../include/linux/fortify-string.h:328:25: warning: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
> > > 328 | __write_overflow_field(p_size_field, size);
> > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
And moar inline_hdr.start:
if (attr.ihs) {
memcpy(eseg->inline_hdr.start, skb->data, attr.ihs);
eseg->inline_hdr.sz = cpu_to_be16(attr.ihs);
dseg += wqe_attr.ds_cnt_inl;
}
again, a split:
memcpy(eseg->inline_hdr.start, skb->data, sizeof(eseg->inline_hdr.start));
eseg->inline_hdr.sz = cpu_to_be16(attr.ihs);
memcpy(dseg, skb->data + sizeof(eseg->inline_hdr.start), ihs - sizeof(eseg->inline_hdr.start));
dseg += wqe_attr.ds_cnt_inl;
And the same bounds questions come up.
It'd be really nice to get some kind of generalized "copy out of
skb->data with bounds checking that may likely all get reduced to
constant checks".
--
Kees Cook
next prev parent reply other threads:[~2022-05-07 7:46 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-06 15:30 [PATCH v4 net-next 00/12] tcp: BIG TCP implementation Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 01/12] net: add IFLA_TSO_{MAX_SIZE|SEGS} attributes Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 02/12] ipv6: add IFLA_GSO_IPV6_MAX_SIZE Eric Dumazet
2022-05-06 20:48 ` Alexander H Duyck
2022-05-06 21:20 ` Eric Dumazet
2022-05-06 21:37 ` Alexander Duyck
2022-05-06 21:50 ` Eric Dumazet
2022-05-06 22:16 ` Alexander Duyck
2022-05-06 22:25 ` Eric Dumazet
2022-05-06 22:26 ` Jakub Kicinski
2022-05-06 22:46 ` Alexander Duyck
2022-05-06 15:30 ` [PATCH v4 net-next 03/12] tcp_cubic: make hystart_ack_delay() aware of BIG TCP Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 04/12] ipv6: add struct hop_jumbo_hdr definition Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 05/12] ipv6/gso: remove temporary HBH/jumbo header Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 06/12] ipv6/gro: insert " Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 07/12] ipv6: add IFLA_GRO_IPV6_MAX_SIZE Eric Dumazet
2022-05-06 21:06 ` Alexander H Duyck
2022-05-06 21:22 ` Eric Dumazet
2022-05-06 22:01 ` Alexander Duyck
2022-05-06 22:08 ` Eric Dumazet
2022-05-09 18:17 ` [PATCH 0/2] Replacements for patches 2 and 7 in Big TCP series Alexander Duyck
2022-05-09 18:17 ` [PATCH 1/2] net: Allow gso_max_size to exceed 65536 Alexander Duyck
2022-05-09 18:17 ` [PATCH 2/2] net: Allow gro_max_size " Alexander Duyck
2022-05-09 18:54 ` [PATCH 0/2] Replacements for patches 2 and 7 in Big TCP series Eric Dumazet
2022-05-09 20:21 ` Alexander H Duyck
2022-05-09 20:31 ` Eric Dumazet
2022-05-09 21:05 ` Alexander Duyck
2022-05-06 15:30 ` [PATCH v4 net-next 08/12] ipv6: Add hop-by-hop header to jumbograms in ip6_output Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 09/12] net: loopback: enable BIG TCP packets Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 10/12] veth: " Eric Dumazet
2022-05-06 22:33 ` Jakub Kicinski
2022-05-06 15:30 ` [PATCH v4 net-next 11/12] mlx4: support " Eric Dumazet
2022-05-06 15:30 ` [PATCH v4 net-next 12/12] mlx5: " Eric Dumazet
2022-05-06 22:34 ` Jakub Kicinski
2022-05-07 0:32 ` Eric Dumazet
2022-05-07 1:54 ` Jakub Kicinski
2022-05-07 1:54 ` Jakub Kicinski
2022-05-07 2:10 ` Eric Dumazet
2022-05-07 2:37 ` Jakub Kicinski
2022-05-07 2:43 ` Eric Dumazet
2022-05-07 7:16 ` Kees Cook
2022-05-07 7:23 ` Kees Cook
2022-05-07 6:57 ` Kees Cook
2022-05-07 7:46 ` Kees Cook [this message]
2022-05-07 11:19 ` Eric Dumazet
2022-05-09 8:05 ` David Laight
2022-05-09 23:20 ` Kees Cook
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