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[97.115.123.245]) by smtp.gmail.com with ESMTPSA id n25sm7513764otj.76.2019.02.20.16.12.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Feb 2019 16:12:28 -0800 (PST) Subject: Re: [PATCH net] net: ip6_gre: fix possible NULL pointer dereference in ip6erspan_set_version To: Lorenzo Bianconi , davem@davemloft.net Cc: netdev@vger.kernel.org, syzbot+30191cf1057abd3064af@syzkaller.appspotmail.com References: <367cdc7c2c859abccfe67eee36cd97f9bf0b2544.1550620650.git.lorenzo.bianconi@redhat.com> From: Gregory Rose Message-ID: Date: Wed, 20 Feb 2019 16:12:26 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <367cdc7c2c859abccfe67eee36cd97f9bf0b2544.1550620650.git.lorenzo.bianconi@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2/20/2019 12:23 AM, Lorenzo Bianconi wrote: > Fix a possible NULL pointer dereference in ip6erspan_set_version checking > nlattr data pointer > > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 7549 Comm: syz-executor432 Not tainted 5.0.0-rc6-next-20190218 > #37 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:ip6erspan_set_version+0x5c/0x350 net/ipv6/ip6_gre.c:1726 > Code: 07 38 d0 7f 08 84 c0 0f 85 9f 02 00 00 49 8d bc 24 b0 00 00 00 c6 43 > 54 01 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f > 85 9a 02 00 00 4d 8b ac 24 b0 00 00 00 4d 85 ed 0f > RSP: 0018:ffff888089ed7168 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: ffff8880869d6e58 RCX: 0000000000000000 > RDX: 0000000000000016 RSI: ffffffff862736b4 RDI: 00000000000000b0 > RBP: ffff888089ed7180 R08: 1ffff11010d3adcb R09: ffff8880869d6e58 > R10: ffffed1010d3add5 R11: ffff8880869d6eaf R12: 0000000000000000 > R13: ffffffff8931f8c0 R14: ffffffff862825d0 R15: ffff8880869d6e58 > FS: 0000000000b3d880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000020000184 CR3: 0000000092cc5000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ip6erspan_newlink+0x66/0x7b0 net/ipv6/ip6_gre.c:2210 > __rtnl_newlink+0x107b/0x16c0 net/core/rtnetlink.c:3176 > rtnl_newlink+0x69/0xa0 net/core/rtnetlink.c:3234 > rtnetlink_rcv_msg+0x465/0xb00 net/core/rtnetlink.c:5192 > netlink_rcv_skb+0x17a/0x460 net/netlink/af_netlink.c:2485 > rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5210 > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] > netlink_unicast+0x536/0x720 net/netlink/af_netlink.c:1336 > netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1925 > sock_sendmsg_nosec net/socket.c:621 [inline] > sock_sendmsg+0xdd/0x130 net/socket.c:631 > ___sys_sendmsg+0x806/0x930 net/socket.c:2136 > __sys_sendmsg+0x105/0x1d0 net/socket.c:2174 > __do_sys_sendmsg net/socket.c:2183 [inline] > __se_sys_sendmsg net/socket.c:2181 [inline] > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2181 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x440159 > Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007fffa69156e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440159 > RDX: 0000000000000000 RSI: 0000000020001340 RDI: 0000000000000003 > RBP: 00000000006ca018 R08: 0000000000000001 R09: 00000000004002c8 > R10: 0000000000000011 R11: 0000000000000246 R12: 00000000004019e0 > R13: 0000000000401a70 R14: 0000000000000000 R15: 0000000000000000 > Modules linked in: > ---[ end trace 09f8a7d13b4faaa1 ]--- > RIP: 0010:ip6erspan_set_version+0x5c/0x350 net/ipv6/ip6_gre.c:1726 > Code: 07 38 d0 7f 08 84 c0 0f 85 9f 02 00 00 49 8d bc 24 b0 00 00 00 c6 43 > 54 01 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f > 85 9a 02 00 00 4d 8b ac 24 b0 00 00 00 4d 85 ed 0f > RSP: 0018:ffff888089ed7168 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: ffff8880869d6e58 RCX: 0000000000000000 > RDX: 0000000000000016 RSI: ffffffff862736b4 RDI: 00000000000000b0 > RBP: ffff888089ed7180 R08: 1ffff11010d3adcb R09: ffff8880869d6e58 > R10: ffffed1010d3add5 R11: ffff8880869d6eaf R12: 0000000000000000 > R13: ffffffff8931f8c0 R14: ffffffff862825d0 R15: ffff8880869d6e58 > FS: 0000000000b3d880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000020000184 CR3: 0000000092cc5000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Fixes: 4974d5f678ab ("net: ip6_gre: initialize erspan_ver just for erspan tunnels") > Reported-and-tested-by: syzbot+30191cf1057abd3064af@syzkaller.appspotmail.com > Signed-off-by: Lorenzo Bianconi > --- > net/ipv6/ip6_gre.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c > index 43890898b0b5..4b9dd5e88329 100644 > --- a/net/ipv6/ip6_gre.c > +++ b/net/ipv6/ip6_gre.c > @@ -1722,6 +1722,9 @@ static int ip6erspan_tap_validate(struct nlattr *tb[], struct nlattr *data[], > static void ip6erspan_set_version(struct nlattr *data[], > struct __ip6_tnl_parm *parms) > { > + if (!data) > + return; > + > parms->erspan_ver = 1; > if (data[IFLA_GRE_ERSPAN_VER]) > parms->erspan_ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]); Oh right.  Yes, that's needed. Thanks! Reviewed-by: Greg Rose