netdev - Re: [bug report] ipv6: addrconf: add per netns perturbation in inet6_addr

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Message-ID: <CANn89iK=vTgVH-J2b5Gfb7Jbq1NVqZ-dp0vo8iG+_iKxO-H-+A@mail.gmail.com>
Date:   Sat, 4 Nov 2017 07:24:09 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        netdev <netdev@...r.kernel.org>
Cc:     kernel-janitors@...r.kernel.org
Subject: Re: [bug report] ipv6: addrconf: add per netns perturbation in inet6_addr_hash()

On Sat, Nov 4, 2017 at 7:13 AM, Eric Dumazet <edumazet@...gle.com> wrote:
> On Sat, Nov 4, 2017 at 1:31 AM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
>> Hello Eric Dumazet,
>>
>> The patch 3f27fb23219e: "ipv6: addrconf: add per netns perturbation
>> in inet6_addr_hash()" from Oct 23, 2017, leads to the following
>> static checker warning:
>>
>>         net/core/pktgen.c:2169 pktgen_setup_inject()
>>         error: buffer overflow 'pkt_dev->cur_in6_saddr.in6_u.u6_addr8' 16 <= 255
>>
>> net/core/pktgen.c
>>   2157          if (pkt_dev->flags & F_IPV6) {
>>   2158                  int i, set = 0, err = 1;
>>   2159                  struct inet6_dev *idev;
>>   2160
>>   2161                  if (pkt_dev->min_pkt_size == 0) {
>>   2162                          pkt_dev->min_pkt_size = 14 + sizeof(struct ipv6hdr)
>>   2163                                                  + sizeof(struct udphdr)
>>   2164                                                  + sizeof(struct pktgen_hdr)
>>   2165                                                  + pkt_dev->pkt_overhead;
>>   2166                  }
>>   2167
>>   2168                  for (i = 0; i < IN6_ADDR_HSIZE; i++)
>>                                         ^^^^^^^^^^^^^^
>> My guess is that this is the wrong test here, but I don't know for sure.
>>
>>   2169                          if (pkt_dev->cur_in6_saddr.s6_addr[i]) {
>>                                                            ^^^^^^^^^^
>> This used to work but now that IN6_ADDR_HSIZE is 256 instead of 16 we're
>> reading beyond the end of the array.
>>
>>   2170                                  set = 1;
>>   2171                                  break;
>>   2172                          }
>>   2173
>>   2174                  if (!set) {
>>   2175
>>   2176                          /*
>>   2177                           * Use linklevel address if unconfigured.
>>   2178                           *
>>   2179                           * use ipv6_get_lladdr if/when it's get exported
>>   2180                           */
>>   2181
>>
>> regards,
>> dan carpenter
>
> pktgen is obviously wrong.
>
> Thanks for the report.

I am travelling to Seoul for netconf/netdev, please send this patch in
an official way.

Thanks !

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 6e1e10ff433a5f4097d1d4b33848ab13d4e005c6..e3fa53a07d34b3e5f6b438e08b440f520b3cd6d4
100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2165,7 +2165,7 @@ static void pktgen_setup_inject(struct
pktgen_dev *pkt_dev)
                                                + pkt_dev->pkt_overhead;
                }

-               for (i = 0; i < IN6_ADDR_HSIZE; i++)
+               for (i = 0; i < sizeof(struct in6_addr); i++)
                        if (pkt_dev->cur_in6_saddr.s6_addr[i]) {
                                set = 1;
                                break;