general protection fault in macsec_upd_offload

[syzbot <syzbot+7022ab7c383875c17eff@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    304e0242 net_sched: add a temporary refcnt for struct tcin..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=17a6940be00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8c1e98458335a7d1
dashboard link: https://syzkaller.appspot.com/bug?extid=7022ab7c383875c17eff
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1099dadbe00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12a63197e00000

The bug was bisected to:

commit 01cacb00b35cb62b139f07d5f84bcf0eeda8eff6
Author: Paolo Abeni <pabeni@redhat.com>
Date:   Fri Mar 27 21:48:51 2020 +0000

    mptcp: add netlink-based PM

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16133ebde00000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=15133ebde00000
console output: https://syzkaller.appspot.com/x/log.txt?x=11133ebde00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7022ab7c383875c17eff@syzkaller.appspotmail.com
Fixes: 01cacb00b35c ("mptcp: add netlink-based PM")

batman_adv: batadv0: Interface activated: batadv_slave_1
netlink: 'syz-executor343': attribute type 1 has an invalid length.
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 7006 Comm: syz-executor343 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:nla_get_u8 include/net/netlink.h:1543 [inline]
RIP: 0010:macsec_upd_offload+0x1c9/0x5a0 drivers/net/macsec.c:2597
Code: fd 00 f0 ff ff 0f 87 23 03 00 00 e8 01 c5 d0 fc 48 8b 5c 24 38 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 04 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 1b 03 00 00
RSP: 0018:ffffc90001797558 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff84a2244d
RDX: 0000000000000000 RSI: ffffffff84a2245f RDI: 0000000000000004
RBP: ffff8880a8372000 R08: ffff888095cae5c0 R09: ffffc90001797588
R10: fffff520002f2eb3 R11: ffffc9000179759f R12: 0000000000000000
R13: ffff88809ffaff80 R14: 1ffff920002f2eab R15: 0000000000000000
FS:  0000000000a6a880(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdd4d1316c0 CR3: 0000000093074000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 genl_family_rcv_msg_doit net/netlink/genetlink.c:673 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:718 [inline]
 genl_rcv_msg+0x627/0xdf0 net/netlink/genetlink.c:735
 netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:746
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6bf/0x7e0 net/socket.c:2362
 ___sys_sendmsg+0x100/0x170 net/socket.c:2416
 __sys_sendmsg+0xec/0x1b0 net/socket.c:2449
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x4438a9
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 6b 0e fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffdc14392d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004438a9
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007ffdc14392f0 R08: 00000000bb1414ac R09: 00000000bb1414ac
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdc1439320
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 98b6a7926fe123d8 ]---
RIP: 0010:nla_get_u8 include/net/netlink.h:1543 [inline]
RIP: 0010:macsec_upd_offload+0x1c9/0x5a0 drivers/net/macsec.c:2597
Code: fd 00 f0 ff ff 0f 87 23 03 00 00 e8 01 c5 d0 fc 48 8b 5c 24 38 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 04 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 1b 03 00 00
RSP: 0018:ffffc90001797558 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff84a2244d
RDX: 0000000000000000 RSI: ffffffff84a2245f RDI: 0000000000000004
RBP: ffff8880a8372000 R08: ffff888095cae5c0 R09: ffffc90001797588
R10: fffff520002f2eb3 R11: ffffc9000179759f R12: 0000000000000000
R13: ffff88809ffaff80 R14: 1ffff920002f2eab R15: 0000000000000000
FS:  0000000000a6a880(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdd4d1316c0 CR3: 0000000093074000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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