netdev - Re: [PATCH net] net: ip6_gre: fix possible NULL pointer dereference in ip6erspan_set

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Message-ID: <b9075671-8630-f815-b634-5514a96455ca@gmail.com>
Date:   Wed, 20 Feb 2019 16:12:26 -0800
From:   Gregory Rose <gvrose8192@...il.com>
To:     Lorenzo Bianconi <lorenzo.bianconi@...hat.com>, davem@...emloft.net
Cc:     netdev@...r.kernel.org,
        syzbot+30191cf1057abd3064af@...kaller.appspotmail.com
Subject: Re: [PATCH net] net: ip6_gre: fix possible NULL pointer dereference
 in ip6erspan_set_version


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@...kaller.appspotmail.com
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
> ---
>   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 <gvrose8192@...il.com>