general protection fault in sctp_timeout_obj_to_nlattr

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 4d552acf Linux 4.19.34
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14610dbb200000
kernel config: https://syzkaller.appspot.com/x/.config?x=c95a88291f095edd
dashboard link: https://syzkaller.appspot.com/bug?extid=d2cd52822fbbdc429d34
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f8aa5b200000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13b2d4d3200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d2cd52...@syzkaller.appspotmail.com

audit: type=1400 audit(1555020875.773:37): avc: denied { create } for
pid=8058 comm="syz-executor771"
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_netfilter_socket permissive=1
netlink: 'syz-executor771': attribute type 2 has an invalid length.
audit: type=1400 audit(1555020875.773:38): avc: denied { write } for
pid=8058 comm="syz-executor771"
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_netfilter_socket permissive=1
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: 0 PID: 8058 Comm: syz-executor771 Not tainted 4.19.34 #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:sctp_timeout_obj_to_nlattr+0x96/0x170
net/netfilter/nf_conntrack_proto_sctp.c:628
Code: f3 65 48 8b 14 25 28 00 00 00 48 89 55 d0 31 d2 48 89 85 70 ff ff ff
e8 b8 cd d3 fb 48 8b 8d 70 ff ff ff 48 89 d8 48 c1 e8 03 <0f> b6 14 08 48
89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 a3
RSP: 0018:ffff88808fe2f3c8 EFLAGS: 00010247
RAX: 0000000000000000 RBX: 0000000000000004 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffffffff85976988 RDI: 1ffff11011fc5e7b
RBP: ffff88808fe2f460 R08: ffff88809994c200 R09: ffff888096fa41e8
R10: ffffed1012df483c R11: ffff888096fa41e0 R12: ffffffff87e13780
R13: 0000000000000001 R14: ffff8880a16f6b80 R15: ffff88808fe2f438
FS: 00000000022a1880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000000 CR3: 0000000092c12000 CR4: 00000000001406f0
Call Trace:
cttimeout_default_fill_info net/netfilter/nfnetlink_cttimeout.c:424
[inline]
cttimeout_default_get+0x69a/0xa80 net/netfilter/nfnetlink_cttimeout.c:471
nfnetlink_rcv_msg+0xd12/0xfe0 net/netfilter/nfnetlink.c:228
netlink_rcv_skb+0x180/0x460 net/netlink/af_netlink.c:2454
nfnetlink_rcv+0x1c0/0x460 net/netfilter/nfnetlink.c:560
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x53c/0x720 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1908
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xdd/0x130 net/socket.c:632
___sys_sendmsg+0x806/0x930 net/socket.c:2115
__sys_sendmsg+0x105/0x1d0 net/socket.c:2153
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2160
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4401e9
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:00007ffe2469d9b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401e9
RDX: 0000000000000000 RSI: 0000000020dddfc8 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a70
R13: 0000000000401b00 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace d21be1f01923f21d ]---
RIP: 0010:sctp_timeout_obj_to_nlattr+0x96/0x170
net/netfilter/nf_conntrack_proto_sctp.c:628
Code: f3 65 48 8b 14 25 28 00 00 00 48 89 55 d0 31 d2 48 89 85 70 ff ff ff
e8 b8 cd d3 fb 48 8b 8d 70 ff ff ff 48 89 d8 48 c1 e8 03 <0f> b6 14 08 48
89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 a3
RSP: 0018:ffff88808fe2f3c8 EFLAGS: 00010247
RAX: 0000000000000000 RBX: 0000000000000004 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffffffff85976988 RDI: 1ffff11011fc5e7b
RBP: ffff88808fe2f460 R08: ffff88809994c200 R09: ffff888096fa41e8
R10: ffffed1012df483c R11: ffff888096fa41e0 R12: ffffffff87e13780
R13: 0000000000000001 R14: ffff8880a16f6b80 R15: ffff88808fe2f438
FS: 00000000022a1880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 0000000092c12000 CR4: 00000000001406f0


---
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[syzbot]

syzbot suspects this bug was fixed by commit:

commit ab69a230421065b48ef93d3e6daf332e71c931dc
Author: David S. Miller <da...@davemloft.net>
Date: Fri May 17 19:15:05 2019 +0000

Revert "tipc: fix modprobe tipc failed after switch order of device
registration"

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15ff1712e00000
start commit: 4d552acf Linux 4.19.34
git tree: linux-4.19.y

kernel config: https://syzkaller.appspot.com/x/.config?x=c95a88291f095edd
dashboard link: https://syzkaller.appspot.com/bug?extid=d2cd52822fbbdc429d34

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f8aa5b200000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13b2d4d3200000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: Revert "tipc: fix modprobe tipc failed after switch order of
device registration"

For information about bisection process see: https://goo.gl/tpsmEJ#bisection