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Message-ID: <CA+_ehUwbUYc6GBGx1VFfqknWrFTk=Xm7NmMUhbyxMSBE4KdnjQ@mail.gmail.com>
Date: Tue, 16 Nov 2021 14:30:59 +0100
From: Ansuel Smith <ansuelsmth@...il.com>
To: Dan Carpenter <dan.carpenter@...cle.com>
Cc: kbuild@...ts.01.org, kernel test robot <lkp@...el.com>,
kbuild-all@...ts.01.org, open list <linux-kernel@...r.kernel.org>
Subject: Re: drivers/net/dsa/qca8k.c:944 qca8k_parse_port_config() error:
testing array offset 'cpu_port_index' after use.
> On Mon, Nov 15, 2021 at 07:08:30PM +0100, Ansuel Smith wrote:
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head: debe436e77c72fcee804fb867f275e6d31aa999c
> > > commit: 5654ec78dd7e64b1e04777b24007344329e6a63b net: dsa: qca8k: rework rgmii delay logic and scan for cpu port 6
> > > config: i386-randconfig-m021-20211025 (attached as .config)
> > > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@...el.com>
> > > Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> > >
> >
> > This should already be fixed by 06dd34a628ae5b6a839b757e746de165d6789ca8
> > Can you confirm this?
> >
>
> No, it doesn't fix the problem. The check is either useless and should
> be removed or there is an out of bounds bug. Checking for an out of
> bounds *after* you've already written to the memory is *never* useful.
>
> regards,
> dan carpenter
>
Again sorry if I insist and I'm 99% missing something.
There was an out of bounds bug.
It was fixed by 06dd34a628ae5b6a839b757e746de165d6789ca8 by
starting the counter to -1.
The extra check is useless, yes.
> > > smatch warnings:
> > > drivers/net/dsa/qca8k.c:944 qca8k_parse_port_config() error: testing array offset 'cpu_port_index' after use.
> > >
> > > vim +/cpu_port_index +944 drivers/net/dsa/qca8k.c
> > >
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 934 static int
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 935 qca8k_parse_port_config(struct qca8k_priv *priv)
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 936 {
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 937 int port, cpu_port_index = 0, ret;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 938 struct device_node *port_dn;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 939 phy_interface_t mode;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 940 struct dsa_port *dp;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 941 u32 delay;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 942
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 943 /* We have 2 CPU port. Check them */
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 @944 for (port = 0; port < QCA8K_NUM_PORTS && cpu_port_index < QCA8K_NUM_CPU_PORTS; port++) {
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > Assume cpu_port_index = QCA8K_NUM_CPU_PORTS - 1;
> > >
> > >
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 945 /* Skip every other port */
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 946 if (port != 0 && port != 6)
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 947 continue;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 948
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 949 dp = dsa_to_port(priv->ds, port);
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 950 port_dn = dp->dn;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 951 cpu_port_index++;
> > > ^^^^^^^^^^^^^^^^^
> > > cpu_port_index is now out of bounds.
> > >
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 952
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 953 if (!of_device_is_available(port_dn))
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 954 continue;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 955
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 956 ret = of_get_phy_mode(port_dn, &mode);
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 957 if (ret)
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 958 continue;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 959
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 960 switch (mode) {
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 961 case PHY_INTERFACE_MODE_RGMII:
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 962 case PHY_INTERFACE_MODE_RGMII_ID:
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 963 case PHY_INTERFACE_MODE_RGMII_TXID:
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 964 case PHY_INTERFACE_MODE_RGMII_RXID:
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 965 delay = 0;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 966
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 967 if (!of_property_read_u32(port_dn, "tx-internal-delay-ps", &delay))
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 968 /* Switch regs accept value in ns, convert ps to ns */
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 969 delay = delay / 1000;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 970 else if (mode == PHY_INTERFACE_MODE_RGMII_ID ||
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 971 mode == PHY_INTERFACE_MODE_RGMII_TXID)
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 972 delay = 1;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 973
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 974 if (delay > QCA8K_MAX_DELAY) {
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 975 dev_err(priv->dev, "rgmii tx delay is limited to a max value of 3ns, setting to the max value");
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 976 delay = 3;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 977 }
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 978
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 979 priv->rgmii_tx_delay[cpu_port_index] = delay;
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > Out of bounds
> > >
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 980
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 981 delay = 0;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 982
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 983 if (!of_property_read_u32(port_dn, "rx-internal-delay-ps", &delay))
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 984 /* Switch regs accept value in ns, convert ps to ns */
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 985 delay = delay / 1000;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 986 else if (mode == PHY_INTERFACE_MODE_RGMII_ID ||
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 987 mode == PHY_INTERFACE_MODE_RGMII_RXID)
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 988 delay = 2;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 989
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 990 if (delay > QCA8K_MAX_DELAY) {
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 991 dev_err(priv->dev, "rgmii rx delay is limited to a max value of 3ns, setting to the max value");
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 992 delay = 3;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 993 }
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 994
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 995 priv->rgmii_rx_delay[cpu_port_index] = delay;
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > Out of bounds
> > >
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 996
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 997 break;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 998 case PHY_INTERFACE_MODE_SGMII:
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 999 if (of_property_read_bool(port_dn, "qca,sgmii-txclk-falling-edge"))
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1000 priv->sgmii_tx_clk_falling_edge = true;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1001
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1002 if (of_property_read_bool(port_dn, "qca,sgmii-rxclk-falling-edge"))
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1003 priv->sgmii_rx_clk_falling_edge = true;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 1004
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 1005 break;
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 1006 default:
> > > 5654ec78dd7e64 Ansuel Smith 2021-10-14 1007 continue;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1008 }
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1009 }
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1010
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1011 return 0;
> > > 6c43809bf1bee7 Ansuel Smith 2021-10-14 1012 }
> > >
> > > ---
> > > 0-DAY CI Kernel Test Service, Intel Corporation
> > > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
> > >
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