Re: general protection fault in sctp_stream_free

[Eric Biggers]

On Sun, Nov 05, 2017 at 01:35:02AM -0700, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on
> 2a171788ba7bb61995e98e8163204fc7880f63b2
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> 
> 
> 
> 
> R13: 00007ff7d3281b58 R14: 00000000004b7560 R15: 0000000000000000
> kasan: CONFIG_KASAN_INLINE enabled
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 1 PID: 17823 Comm: syz-executor4 Not tainted 4.14.0-rc7+ #109
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> task: ffff8801c6002380 task.stack: ffff8801c5fe0000
> RIP: 0010:sctp_stream_free+0xc3/0x1b0 net/sctp/stream.c:209
> RSP: 0018:ffff8801c5fe6fa0 EFLAGS: 00010202
> RAX: 0000000000000000 RBX: ffff8801c33fd0b0 RCX: ffffc90003989000
> RDX: 0000000000000001 RSI: ffffffff84837f78 RDI: 0000000000000008
> RBP: ffff8801c5fe6fe0 R08: 0000000000000000 R09: 1ffff10038bfcd69
> R10: 000000009cb59878 R11: 00000000f5f9e5c7 R12: 0000000000000000
> R13: 0000000000000000 R14: dffffc0000000000 R15: ffffed003867fa16
> FS:  00007ff7d3282700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020b50ffc CR3: 00000001c4a5c000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  sctp_association_free+0x301/0x930 net/sctp/associola.c:367
>  sctp_sf_do_unexpected_init.isra.28+0x67e/0x13b0
> net/sctp/sm_statefuns.c:1589
>  sctp_sf_do_5_2_1_siminit+0x35/0x40 net/sctp/sm_statefuns.c:1645
>  sctp_do_sm+0x18a/0x6a30 net/sctp/sm_sideeffect.c:1190
>  sctp_assoc_bh_rcv+0x283/0x4b0 net/sctp/associola.c:1065
>  sctp_inq_push+0x23b/0x300 net/sctp/inqueue.c:95
>  sctp_backlog_rcv+0x177/0xaa0 net/sctp/input.c:350
>  sk_backlog_rcv include/net/sock.h:912 [inline]
>  __release_sock+0x124/0x360 net/core/sock.c:2266
>  release_sock+0xa4/0x2a0 net/core/sock.c:2778
>  sctp_sendmsg+0x18d1/0x32b0 net/sctp/socket.c:2051
>  inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
>  sock_sendmsg_nosec net/socket.c:633 [inline]
>  sock_sendmsg+0xca/0x110 net/socket.c:643
>  SYSC_sendto+0x352/0x5a0 net/socket.c:1750
>  SyS_sendto+0x40/0x50 net/socket.c:1718
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
> RIP: 0033:0x452869
> RSP: 002b:00007ff7d3281be8 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 00000000007580d8 RCX: 0000000000452869
> RDX: 0000000000000001 RSI: 00000000206a6000 RDI: 0000000000000013
> RBP: 00007ff7d3281a20 R08: 000000002064b000 R09: 000000000000001c
> R10: 0000000020000040 R11: 0000000000000212 R12: 00000000004b7550
> R13: 00007ff7d3281b58 R14: 00000000004b7560 R15: 0000000000000000
> Code: 48 c1 e8 03 4c 01 f0 48 89 45 d0 e8 d8 b4 ea fc 41 80 3f 00 0f 85 f1
> 00 00 00 48 8b 03 4c 01 e8 48 8d 78 08 48 89 fa 48 c1 ea 03 <42> 80 3c 32 00
> 0f 85 c3 00 00 00 48 8b 78 08 41 83 c4 01 e8 85
> RIP: sctp_stream_free+0xc3/0x1b0 net/sctp/stream.c:209 RSP: ffff8801c5fe6fa0
> ---[ end trace cf03319dc427fb51 ]---
> 
> 
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
> Please credit me with: Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
> 
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title

This crash seems to have stopped occurring now.  I presume it was fixed by:

#syz fix: sctp: fix error path in sctp_stream_init