general protection fault in sctp_sched_rr_dequeue

[syzbot <syzbot+4c9934f20522c0efd657@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    63bdf4284c38 Merge branch 'linus' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x\x100347cb200000
kernel config:  https://syzkaller.appspot.com/x/.config?x‡2be05707464aaa
dashboard link: https://syzkaller.appspot.com/bug?extidL9934f20522c0efd657
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x\x11cd9b03200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x\x127de8e7200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4c9934f20522c0efd657@syzkaller.appspotmail.com

kauditd_printk_skb: 2 callbacks suppressed
audit: type\x1400 audit(1551833288.424:35): avc:  denied  { map } for   
pid€35 comm="bash" path="/bin/bash" dev="sda1" ino\x1457  
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
audit: type\x1400 audit(1551833294.934:36): avc:  denied  { map } for   
pid€47 comm="syz-executor778" path="/root/syz-executor778173561"  
dev="sda1" ino\x16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file 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: 1 PID: 8047 Comm: syz-executor778 Not tainted 5.0.0+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:sctp_sched_rr_dequeue+0xd3/0x170 net/sctp/stream_sched_rr.c:141
Code: ea 03 80 3c 02 00 0f 85 a2 00 00 00 48 8b 5b 08 e8 62 20 ee fa 48 8d  
7b 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75  
53 4c 8b 6b 30 4c 89 e7 49 83 ed 18 4c 89 ee e8 b4
RSP: 0018:ffff88809eacf040 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8679cd9f
RDX: 0000000000000006 RSI: ffffffff8681c41e RDI: 0000000000000030
RBP: ffff88809eacf058 R08: ffff8880a12bc300 R09: 0000000000000002
R10: ffffed1015d25bcf R11: ffff8880ae92de7b R12: ffff88807cae6ca0
R13: ffff88807cae6580 R14: dffffc0000000000 R15: ffff88809eacf198
FS:  0000000001865880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055af2d491150 CR3: 000000008dd7b000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  sctp_outq_dequeue_data net/sctp/outqueue.c:90 [inline]
  sctp_outq_flush_data net/sctp/outqueue.c:1079 [inline]
  sctp_outq_flush+0xba2/0x2790 net/sctp/outqueue.c:1205
  sctp_outq_uncork+0x6c/0x80 net/sctp/outqueue.c:772
  sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1820 [inline]
  sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
  sctp_do_sm+0x513/0x5390 net/sctp/sm_sideeffect.c:1191
  sctp_assoc_bh_rcv+0x343/0x660 net/sctp/associola.c:1074
  sctp_inq_push+0x1ea/0x290 net/sctp/inqueue.c:95
  sctp_backlog_rcv+0x189/0xbc0 net/sctp/input.c:354
  sk_backlog_rcv include/net/sock.h:937 [inline]
  __release_sock+0x12e/0x3a0 net/core/sock.c:2413
  release_sock+0x59/0x1c0 net/core/sock.c:2929
  sctp_wait_for_connect+0x316/0x540 net/sctp/socket.c:8999
  sctp_sendmsg_to_asoc+0x13e2/0x17d0 net/sctp/socket.c:1968
  sctp_sendmsg+0x10a9/0x17e0 net/sctp/socket.c:2114
  inet_sendmsg+0x147/0x5d0 net/ipv4/af_inet.c:798
  sock_sendmsg_nosec net/socket.c:622 [inline]
  sock_sendmsg+0xdd/0x130 net/socket.c:632
  ___sys_sendmsg+0x806/0x930 net/socket.c:2137
  __sys_sendmsg+0x105/0x1d0 net/socket.c:2175
  __do_sys_sendmsg net/socket.c:2184 [inline]
  __se_sys_sendmsg net/socket.c:2182 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2182
  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:00007fff8801fd38 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440159
RDX: 0000000000000000 RSI: 000000002001afc8 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000002 R09: 00000000004002c8
R10: 0000000000000008 R11: 0000000000000246 R12: 00000000004019e0
R13: 0000000000401a70 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 7cc5803525726c53 ]---
RIP: 0010:sctp_sched_rr_dequeue+0xd3/0x170 net/sctp/stream_sched_rr.c:141
Code: ea 03 80 3c 02 00 0f 85 a2 00 00 00 48 8b 5b 08 e8 62 20 ee fa 48 8d  
7b 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75  
53 4c 8b 6b 30 4c 89 e7 49 83 ed 18 4c 89 ee e8 b4
RSP: 0018:ffff88809eacf040 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8679cd9f
RDX: 0000000000000006 RSI: ffffffff8681c41e RDI: 0000000000000030
RBP: ffff88809eacf058 R08: ffff8880a12bc300 R09: 0000000000000002
R10: ffffed1015d25bcf R11: ffff8880ae92de7b R12: ffff88807cae6ca0
R13: ffff88807cae6580 R14: dffffc0000000000 R15: ffff88809eacf198
FS:  0000000001865880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055af2d491150 CR3: 000000008dd7b000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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