Date:   Mon, 07 Jan 2019 01:54:03 -0800
From:   syzbot <syzbot+a47c5f4c6c00fc1ed16e@...kaller.appspotmail.com>
To:     davem@...emloft.net, dsahern@...il.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        pablo@...filter.org, syzkaller-bugs@...glegroups.com
Subject: KASAN: slab-out-of-bounds Read in dst_dev_put

Hello,

syzbot found the following crash on:

HEAD commit:    f1c2f8857c5a Merge tag 'powerpc-4.21-2' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16b0484f400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=47c29c309c47af16
dashboard link: https://syzkaller.appspot.com/bug?extid=a47c5f4c6c00fc1ed16e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a47c5f4c6c00fc1ed16e@...kaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in dst_dev_put+0x219/0x290 net/core/dst.c:168
Read of size 8 at addr ffff88803291eca8 by task syz-executor0/15230

CPU: 1 PID: 15230 Comm: syz-executor0 Not tainted 4.20.0+ #11
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  <IRQ>
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1db/0x2d0 lib/dump_stack.c:113
  print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
  kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
  dst_dev_put+0x219/0x290 net/core/dst.c:168
  rt_fibinfo_free_cpus net/ipv4/fib_semantics.c:200 [inline]
  free_fib_info_rcu+0x2f4/0x4a0 net/ipv4/fib_semantics.c:217
  __rcu_reclaim kernel/rcu/rcu.h:240 [inline]
  rcu_do_batch kernel/rcu/tree.c:2452 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
  rcu_process_callbacks+0xc4a/0x1680 kernel/rcu/tree.c:2754
  __do_softirq+0x30b/0xb11 kernel/softirq.c:292
  invoke_softirq kernel/softirq.c:373 [inline]
  irq_exit+0x180/0x1d0 kernel/softirq.c:413
  exiting_irq arch/x86/include/asm/apic.h:536 [inline]
  smp_apic_timer_interrupt+0x1b7/0x760 arch/x86/kernel/apic/apic.c:1062
  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
  </IRQ>
RIP: 0010:PageSwapBacked include/linux/page-flags.h:307 [inline]
RIP: 0010:PageSwapCache include/linux/page-flags.h:352 [inline]
RIP: 0010:free_swap_cache mm/swap_state.c:266 [inline]
RIP: 0010:free_pages_and_swap_cache+0x214/0x6a0 mm/swap_state.c:294
Code: 42 43 c4 ff 48 8b b5 d0 fe ff ff 4c 89 e7 48 8b 85 c8 fe ff ff 48 85  
f6 0f 85 28 03 00 00 48 89 bd d0 fe ff ff e8 7c 41 c4 ff <48> 8b bd d0 fe  
ff ff 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 70 03
tls_set_device_offload_rx: netdev lo with no TLS offload
RSP: 0018:ffff88809fabeef0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: ffff88808b6de5c0 RBX: dffffc0000000000 RCX: ffffffff81bdb6ee
RDX: 0000000000000000 RSI: ffffffff81bdb714 RDI: ffffea00027ccc40
RBP: ffff88809fabf040 R08: ffff88808b6de5c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00027ccc40
R13: ffffea00027ccc40 R14: ffffea00027ccc48 R15: ffff88809fabf018
  tlb_flush_mmu_free+0x4e/0x120 mm/mmu_gather.c:74
  zap_pte_range mm/memory.c:1157 [inline]
  zap_pmd_range mm/memory.c:1192 [inline]
  zap_pud_range mm/memory.c:1221 [inline]
  zap_p4d_range mm/memory.c:1242 [inline]
  unmap_page_range+0x1c49/0x25a0 mm/memory.c:1263
  unmap_single_vma+0x19d/0x300 mm/memory.c:1308
  unmap_vmas+0x17c/0x310 mm/memory.c:1339
  exit_mmap+0x2d4/0x5d0 mm/mmap.c:3140
  __mmput kernel/fork.c:1046 [inline]
  mmput+0x240/0x640 kernel/fork.c:1067
tls_set_device_offload_rx: netdev lo with no TLS offload
  exit_mm kernel/exit.c:545 [inline]
  do_exit+0x9d3/0x2650 kernel/exit.c:854
  do_group_exit+0x177/0x430 kernel/exit.c:970
  get_signal+0x8b4/0x19b0 kernel/signal.c:2517
  do_signal+0x91/0x1ea0 arch/x86/kernel/signal.c:816
tls_set_device_offload_rx: netdev lo with no TLS offload
  exit_to_usermode_loop+0x2f7/0x3b0 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457ec9
Code: Bad RIP value.
RSP: 002b:00007fa0c9fcfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffff2 RBX: 0000000000000003 RCX: 0000000000457ec9
RDX: 00000000200001c0 RSI: 0020000000008912 RDI: 0000000000000005
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa0c9fd06d4
R13: 00000000004bf0f5 R14: 00000000004d06d0 R15: 00000000ffffffff
tls_set_device_offload_rx: netdev lo with no TLS offload

Allocated by task 15139:
  save_stack+0x45/0xd0 mm/kasan/common.c:73
  set_track mm/kasan/common.c:85 [inline]
  kasan_kmalloc mm/kasan/common.c:482 [inline]
  kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455
  kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:397
  kmem_cache_alloc_node+0x144/0x710 mm/slab.c:3631
  __alloc_skb+0xf4/0x730 net/core/skbuff.c:196
  alloc_skb include/linux/skbuff.h:1011 [inline]
  nlmsg_new include/net/netlink.h:654 [inline]
  rtmsg_ifinfo_build_skb+0x74/0x1a0 net/core/rtnetlink.c:3407
  rtmsg_ifinfo_event.part.0+0x43/0xe0 net/core/rtnetlink.c:3443
  rtmsg_ifinfo_event net/core/rtnetlink.c:3454 [inline]
  rtmsg_ifinfo+0x8d/0xa0 net/core/rtnetlink.c:3452
  __dev_notify_flags+0x2e9/0x470 net/core/dev.c:7601
  dev_change_flags+0x10d/0x170 net/core/dev.c:7643
  do_setlink+0x17f5/0x3e10 net/core/rtnetlink.c:2492
  __rtnl_newlink+0xd58/0x1a70 net/core/rtnetlink.c:3115
  rtnl_newlink+0x69/0xa0 net/core/rtnetlink.c:3240
  rtnetlink_rcv_msg+0x481/0xc30 net/core/rtnetlink.c:5130
  netlink_rcv_skb+0x17d/0x410 net/netlink/af_netlink.c:2477
  rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5148
  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  netlink_unicast+0x574/0x770 net/netlink/af_netlink.c:1336
  netlink_sendmsg+0xa05/0xf90 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg+0xdd/0x130 net/socket.c:631
  __sys_sendto+0x387/0x5f0 net/socket.c:1788
  __do_sys_sendto net/socket.c:1800 [inline]
  __se_sys_sendto net/socket.c:1796 [inline]
  __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1796
  do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 15139:
  save_stack+0x45/0xd0 mm/kasan/common.c:73
  set_track mm/kasan/common.c:85 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
  kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
  __cache_free mm/slab.c:3485 [inline]
  kmem_cache_free+0x86/0x260 mm/slab.c:3747
  kfree_skbmem net/core/skbuff.c:585 [inline]
  kfree_skbmem+0x14e/0x230 net/core/skbuff.c:579
  __kfree_skb net/core/skbuff.c:642 [inline]
  consume_skb net/core/skbuff.c:701 [inline]
  consume_skb+0x194/0x550 net/core/skbuff.c:695
  netlink_broadcast_filtered+0x6e7/0x16f0 net/netlink/af_netlink.c:1512
  netlink_broadcast net/netlink/af_netlink.c:1534 [inline]
  nlmsg_multicast include/net/netlink.h:734 [inline]
  nlmsg_notify+0x93/0x1c0 net/netlink/af_netlink.c:2520
  rtnl_notify net/core/rtnetlink.c:742 [inline]
  rtmsg_ifinfo_send net/core/rtnetlink.c:3431 [inline]
  rtmsg_ifinfo_event.part.0+0xb0/0xe0 net/core/rtnetlink.c:3446
  rtmsg_ifinfo_event net/core/rtnetlink.c:3454 [inline]
  rtmsg_ifinfo+0x8d/0xa0 net/core/rtnetlink.c:3452
  __dev_notify_flags+0x2e9/0x470 net/core/dev.c:7601
  dev_change_flags+0x10d/0x170 net/core/dev.c:7643
  do_setlink+0x17f5/0x3e10 net/core/rtnetlink.c:2492
  __rtnl_newlink+0xd58/0x1a70 net/core/rtnetlink.c:3115
  rtnl_newlink+0x69/0xa0 net/core/rtnetlink.c:3240
  rtnetlink_rcv_msg+0x481/0xc30 net/core/rtnetlink.c:5130
  netlink_rcv_skb+0x17d/0x410 net/netlink/af_netlink.c:2477
  rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5148
  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  netlink_unicast+0x574/0x770 net/netlink/af_netlink.c:1336
  netlink_sendmsg+0xa05/0xf90 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg+0xdd/0x130 net/socket.c:631
  __sys_sendto+0x387/0x5f0 net/socket.c:1788
  __do_sys_sendto net/socket.c:1800 [inline]
  __se_sys_sendto net/socket.c:1796 [inline]
  __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1796
  do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88803291eb80
  which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 72 bytes to the right of
  224-byte region [ffff88803291eb80, ffff88803291ec60)
The buggy address belongs to the page:
page:ffffea0000ca4780 count:1 mapcount:0 mapping:ffff8880aa16a040 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0001b18448 ffffea0001a2cbc8 ffff8880aa16a040
raw: 0000000000000000 ffff88803291e040 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88803291eb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88803291ec00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> ffff88803291ec80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                   ^
  ffff88803291ed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88803291ed80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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