net/sctp: GPF in sctp_addr_id2transport

[Dmitry Vyukov]

Hello,

The following program triggers GPF in sctp_addr_id2transport:

// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <string.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <linux/sctp.h>

int main()
{
  int sock = socket(AF_INET6, SOCK_SEQPACKET, IPPROTO_SCTP);
  struct sctp_paddrinfo info;
  memset(&info, 0, sizeof(info));
  int sz = sizeof(info);
  getsockopt(sock, IPPROTO_SCTP, SCTP_GET_PEER_ADDR_INFO, &info, &sz);
  return 0;
}


general protection fault: 0000 [#1] SMP KASAN
Modules linked in:
CPU: 2 PID: 2923 Comm: a.out Not tainted 4.10.0-rc7+ #212
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff880066db2400 task.stack: ffff88006b9b8000
RIP: 0010:sctp_addr_id2transport+0xb7/0x350 net/sctp/socket.c:242
RSP: 0018:ffff88006b9bf1d0 EFLAGS: 00010207
RAX: 0000000000000000 RBX: ffff880067e1f000 RCX: 0000000000000017
RDX: dffffc0000000000 RSI: ffff88006b9bf2b4 RDI: 00000000000000bc
RBP: ffff88006b9bf268 R08: ffffed000d737e69 R09: ffffed000d737e69
R10: 0000000000000000 R11: ffffed000d737e68 R12: ffff88006b9bf2b4
R13: ffff88006b9bf200 R14: 1ffff1000d737e3c R15: ffff88006b9bf240
FS:  0000000001f3b880(0000) GS:ffff88006d100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004b2120 CR3: 000000006940a000 CR4: 00000000001406e0
Call Trace:
 sctp_getsockopt_peer_addr_info+0x211/0x620 net/sctp/socket.c:4628
 sctp_getsockopt+0x2813/0x66a0 net/sctp/socket.c:6503
 sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2685
 SYSC_getsockopt net/socket.c:1819 [inline]
 SyS_getsockopt+0x240/0x380 net/socket.c:1801
 entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x436dea
RSP: 002b:00007ffe2c6c19c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 0000000000401780 RCX: 0000000000436dea
RDX: 000000000000000f RSI: 0000000000000084 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffe2c6c19d8 R09: 0000000000000004
R10: 00007ffe2c6c19e0 R11: 0000000000000246 R12: 00000000004002b0
R13: 00007ffe2c6c1b88 R14: 0000000000000002 R15: 0000000000000000
Code: 8d 6f c0 e8 7c 78 fa ff 4c 89 e9 48 8d b8 bc 00 00 00 48 ba 00
00 00 00 00 fc ff df 48 c1 e9 03 c6 04 11 00 48 89 f9 48 c1 e9 03 <0f>
b6 0c 11 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85
RIP: sctp_addr_id2transport+0xb7/0x350 net/sctp/socket.c:242 RSP:
ffff88006b9bf1d0
---[ end trace afb2edc8308e52f6 ]---

On commit 8b1b41ee74f9712c355d66dc105bbea663ae0afd.