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[2003:ea:8f1f:ad00:acff:e553:5e:a443]) by smtp.googlemail.com with ESMTPSA id i8sm4409744wry.90.2021.01.27.12.32.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Jan 2021 12:32:09 -0800 (PST) Subject: Re: [PATCH net] r8169: work around RTL8125 UDP hw bug To: Willem de Bruijn Cc: Jakub Kicinski , David Miller , Realtek linux nic maintainers , "netdev@vger.kernel.org" , xplo.bn@gmail.com References: <3afea922-776b-baf3-634c-9a1e84e8c4c2@gmail.com> From: Heiner Kallweit Message-ID: <5229d00c-1b12-38fb-3f2b-e21f005281ec@gmail.com> Date: Wed, 27 Jan 2021 21:32:06 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 27.01.2021 20:54, Willem de Bruijn wrote: > On Wed, Jan 27, 2021 at 2:40 PM Heiner Kallweit wrote: >> >> On 27.01.2021 19:07, Willem de Bruijn wrote: >>> On Tue, Jan 26, 2021 at 2:40 PM Heiner Kallweit wrote: >>>> >>>> It was reported that on RTL8125 network breaks under heavy UDP load, >>>> e.g. torrent traffic ([0], from comment 27). Realtek confirmed a hw bug >>>> and provided me with a test version of the r8125 driver including a >>>> workaround. Tests confirmed that the workaround fixes the issue. >>>> I modified the original version of the workaround to meet mainline >>>> code style. >>>> >>>> [0] https://bugzilla.kernel.org/show_bug.cgi?id=209839 >>>> >>>> Fixes: f1bce4ad2f1c ("r8169: add support for RTL8125") >>>> Tested-by: xplo >>>> Signed-off-by: Heiner Kallweit >>>> --- >>>> drivers/net/ethernet/realtek/r8169_main.c | 64 ++++++++++++++++++++--- >>>> 1 file changed, 58 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c >>>> index fb67d8f79..90052033b 100644 >>>> --- a/drivers/net/ethernet/realtek/r8169_main.c >>>> +++ b/drivers/net/ethernet/realtek/r8169_main.c >>>> @@ -28,6 +28,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #include >>>> #include >>>> >>>> @@ -4007,17 +4008,64 @@ static int rtl8169_xmit_frags(struct rtl8169_private *tp, struct sk_buff *skb, >>>> return -EIO; >>>> } >>>> >>>> -static bool rtl_test_hw_pad_bug(struct rtl8169_private *tp) >>>> +static bool rtl_skb_is_udp(struct sk_buff *skb) >>>> { >>>> + switch (vlan_get_protocol(skb)) { >>>> + case htons(ETH_P_IP): >>>> + return ip_hdr(skb)->protocol == IPPROTO_UDP; >>>> + case htons(ETH_P_IPV6): >>>> + return ipv6_hdr(skb)->nexthdr == IPPROTO_UDP; >>> >>> This trusts that an skb with given skb->protocol is well behaved. With >>> packet sockets/tun/virtio, that may be false. >>> >>>> + default: >>>> + return false; >>>> + } >>>> +} >>>> + >>>> +#define RTL_MIN_PATCH_LEN 47 >>>> +#define PTP_GEN_PORT 320 >>> >>> Why the two PTP ports? The report is not PTP specific. Also, what does >>> patch mean in this context? >>> >>>> + >>>> +/* see rtl8125_get_patch_pad_len() in r8125 vendor driver */ >>>> +static unsigned int rtl8125_quirk_udp_padto(struct rtl8169_private *tp, >>>> + struct sk_buff *skb) >>>> +{ >>>> + unsigned int padto = 0, len = skb->len; >>>> + >>>> + if (rtl_is_8125(tp) && len < 175 && rtl_skb_is_udp(skb) && >>>> + skb_transport_header_was_set(skb)) { >>> >>> What is 175 here? >>> >>>> + unsigned int trans_data_len = skb_tail_pointer(skb) - >>>> + skb_transport_header(skb); >>>> + >>>> + if (trans_data_len > 3 && trans_data_len < RTL_MIN_PATCH_LEN) { >>> >>> And 3 here, instead of sizeof(struct udphdr) >>> >>>> + u16 dest = ntohs(udp_hdr(skb)->dest); >>>> + >>>> + if (dest == PTP_EV_PORT || dest == PTP_GEN_PORT) >>>> + padto = len + RTL_MIN_PATCH_LEN - trans_data_len; >>>> + } >>>> + >>>> + if (trans_data_len < UDP_HLEN) >>>> + padto = max(padto, len + UDP_HLEN - trans_data_len); >>>> + } >>>> + >>>> + return padto; >>>> +} >>>> + >>>> +static unsigned int rtl_quirk_packet_padto(struct rtl8169_private *tp, >>>> + struct sk_buff *skb) >>>> +{ >>>> + unsigned int padto; >>>> + >>>> + padto = rtl8125_quirk_udp_padto(tp, skb); >>>> + >>>> switch (tp->mac_version) { >>>> case RTL_GIGA_MAC_VER_34: >>>> case RTL_GIGA_MAC_VER_60: >>>> case RTL_GIGA_MAC_VER_61: >>>> case RTL_GIGA_MAC_VER_63: >>>> - return true; >>>> + padto = max_t(unsigned int, padto, ETH_ZLEN); >>>> default: >>>> - return false; >>>> + break; >>>> } >>>> + >>>> + return padto; >>>> } >>>> >>>> static void rtl8169_tso_csum_v1(struct sk_buff *skb, u32 *opts) >>>> @@ -4089,9 +4137,10 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private *tp, >>>> >>>> opts[1] |= transport_offset << TCPHO_SHIFT; >>>> } else { >>>> - if (unlikely(skb->len < ETH_ZLEN && rtl_test_hw_pad_bug(tp))) >>>> - /* eth_skb_pad would free the skb on error */ >>>> - return !__skb_put_padto(skb, ETH_ZLEN, false); >>>> + unsigned int padto = rtl_quirk_packet_padto(tp, skb); >>>> + >>>> + /* skb_padto would free the skb on error */ >>>> + return !__skb_put_padto(skb, padto, false); >>>> } >>>> >>>> return true; >>>> @@ -4268,6 +4317,9 @@ static netdev_features_t rtl8169_features_check(struct sk_buff *skb, >>>> if (skb->len < ETH_ZLEN) >>>> features &= ~NETIF_F_CSUM_MASK; >>>> >>>> + if (rtl_quirk_packet_padto(tp, skb)) >>>> + features &= ~NETIF_F_CSUM_MASK; >>>> + >>>> if (transport_offset > TCPHO_MAX && >>>> rtl_chip_supports_csum_v2(tp)) >>>> features &= ~NETIF_F_CSUM_MASK; >>>> -- >>>> 2.30.0 >>>> >> >> The workaround was provided by Realtek, I just modified it to match >> mainline code style. For your reference I add the original version below. >> I don't know where the magic numbers come from, Realtek releases >> neither data sheets nor errata information. > > Okay. I don't know what is customary for this process. > > But I would address the possible out of bounds read by trusting ip > header integrity in rtl_skb_is_udp. > I don't know tun/virtio et al good enough to judge which header elements may be trustworthy and which may be not. What should be checked where?